Formula library

Calculator formulas

A browsable index of the formulas behind CalculTools calculators. Each formula links to a working calculator page.

Money

employee contribution = salary × contribution%; employer match = salary × min(contribution%, match limit) × match rate

Estimate employer 401k match value from salary, contribution rate, and match rules.IRA Contribution Calculatorfuture value = current growth + future value of annual contributionsEstimate IRA contribution growth over time with regular annual contributions.Traditional vs Roth IRA Calculatorcompare Roth after-tax contribution growth vs Traditional pre-tax growth after retirement taxCompare simplified after-tax retirement value between Traditional IRA and Roth IRA contributions.Bond Price Calculatorbond price = present value of coupons + present value of face valueEstimate a bond price from face value, coupon rate, market yield, and years to maturity.Zero Coupon Bond Calculatorprice = face value ÷ (1 + yield)^yearsCalculate the present price of a zero-coupon bond from face value, yield, and maturity.Treasury Bill Calculatorreturn = face − price; annualized yield ≈ return ÷ price × 365 ÷ daysEstimate T-bill discount yield and investment return from price, face value, and days to maturity.Portfolio Return Calculatorportfolio return = sum(weight × return)Calculate weighted portfolio return from asset weights and returns.Asset Allocation Calculatorasset dollars = portfolio value × allocation percentageConvert portfolio allocation percentages into dollar amounts by asset class.Capital Gains Tax Estimatorgain = (sale price − buy price) × quantity; tax = gain × tax rateEstimate capital gain and tax owed using purchase price, sale price, quantity, and tax rate.After-Tax Return Calculatorafter-tax return = return × (1 − tax rate)Calculate investment return after taxes.Savings Withdrawal Calculatorsimulate monthly growth and withdrawals until balance reaches zeroEstimate how long savings may last with monthly withdrawals and optional growth.Private Mortgage Insurance Calculatormonthly PMI = loan × annual PMI rate ÷ 12Estimate monthly PMI cost from loan amount and annual PMI rate.Interest Only Mortgage Calculatormonthly payment = loan × annual interest rate ÷ 12Calculate the interest-only monthly mortgage payment.Renters Insurance Calculatorannual cost = coverage ÷ 100 × rateEstimate annual and monthly renters insurance cost from coverage and rate.Mortgage Prepayment Calculatorcompare amortization with and without a one-time principal prepaymentEstimate interest savings from an additional one-time mortgage prepayment.Home Sale Profit Calculatorsale profit/cash = sale price − payoff − costs − purchase basis estimateEstimate profit from selling a home after purchase price, improvements, mortgage payoff, and selling costs.Mortgage Comparison Calculatorcompare fixed-rate mortgage payments for two rates and termsCompare two mortgage options by monthly payment and total interest.Debt Consolidation Calculatornew payment uses fixed-rate loan formula; compare with current monthly paymentCompare current debt payments with a consolidated loan payment.

Math

Percentage Calculatorresult = value × percent ÷ 100Calculate percentages, parts, totals, increases, and decreases.Percentage Change Calculatorchange = (new − old) ÷ old × 100Find the percentage increase or decrease from an old value to a new value.Average Calculatoraverage = sum ÷ countCalculate the average of comma-separated numbers.Ratio Calculatorsimplified ratio = a/gcd : b/gcdSimplify a two-number ratio.Fraction Calculatorcalculate using common denominator or fraction operationAdd, subtract, multiply, or divide two fractions.Square Root Calculatorresult = √valueCalculate the square root of a number.Scientific Calculatorpower, root, sin, cos, tan, ln, log10Calculate powers, roots, sine, cosine, tangent, and logarithms.LCM CalculatorLCM = |a × b| ÷ GCD(a,b)Calculate least common multiple of two numbers.GCD CalculatorEuclidean algorithmCalculate greatest common divisor of two numbers.Prime Number Calculatortest divisibility up to √nCheck whether a number is prime.Circle Calculatorarea = πr², circumference = 2πrCalculate circle area and circumference from radius.Triangle Calculatorarea = base × height ÷ 2Calculate triangle area from base and height.Aspect Ratio Calculatornew height = original height × new width ÷ original widthScale width or height while preserving aspect ratio.Permutation CalculatornPr = n! ÷ (n − r)!Calculate permutations nPr.Combination CalculatornCr = n! ÷ (r! × (n − r)!)Calculate combinations nCr.Standard Deviation Calculatorstandard deviation = sqrt(sum((x − mean)^2) ÷ n)Calculate mean, variance, and standard deviation from comma-separated numbers.Statistics Calculatorsummary statistics from a number setCalculate count, sum, mean, median, min, max, and range.Probability Calculatorprobability = favorable ÷ total × 100Calculate probability from favorable outcomes and total outcomes.Quadratic Formula Calculatorx = (-b ± √(b² − 4ac)) ÷ 2aSolve ax² + bx + c = 0 using the quadratic formula.Slope Calculatorslope = (y2 − y1) ÷ (x2 − x1)Find slope from two coordinate points.Pythagorean Theorem Calculatorc = √(a² + b²)Calculate the hypotenuse from two right-triangle legs.Long Division Calculatordividend = divisor × quotient + remainderCalculate quotient and remainder for integer division.Number to Percent Calculatorpercent = number × 100Convert a number or decimal into a percent.Percent to Decimal Calculatordecimal = percent ÷ 100Convert a percent into decimal form.Decimal to Fraction Calculatorfraction ≈ decimal × denominator ÷ denominatorConvert a decimal to an approximate fraction.Fraction to Decimal Calculatordecimal = numerator ÷ denominatorConvert a fraction into decimal and percent form.Rounding Calculatorrounded value = number rounded to selected placesRound a number to a selected number of decimal places.Absolute Value Calculatorabsolute value = distance from zeroCalculate the absolute value of a number.Factorial Calculatorn! = n × (n−1) × ... × 1Calculate n factorial for non-negative integers.Modulo Calculatormodulo = remainder after dividend ÷ divisorCalculate the remainder after division.Linear Equation Calculatorx = (c − b) ÷ aSolve a simple linear equation ax + b = c.Distance Between Points Calculatordistance = √((x2−x1)² + (y2−y1)²)Calculate distance between two coordinate points.Midpoint Calculatormidpoint = ((x1+x2)/2, (y1+y2)/2)Find the midpoint between two coordinate points.Z Score Calculatorz = (value − mean) ÷ standard deviationCalculate a z-score from value, mean, and standard deviation.Variance Calculatorvariance = average squared distance from the meanCalculate population and sample variance from a list of numbers.Percentile Calculatorpercentile value = ranked position in sorted dataEstimate a percentile value from a list of numbers.Sample Size Calculatorn = z² × p(1−p) ÷ e²Estimate sample size for a proportion using confidence and margin of error.Probability Percentage Calculatorpercentage = probability × 100Convert probability to percentage and odds.Mean Median Mode Calculatormean = sum ÷ count; median = middle value; mode = most frequent valueCalculate mean, median, and mode from a list of numbers.Surface Area Calculatorsurface area = 2(lw + lh + wh)Calculate rectangular prism surface area.Geometric Mean Calculatorgeometric mean = nth root of product of n valuesCalculate the geometric mean of positive numbers.Harmonic Mean Calculatorharmonic mean = n ÷ sum(1/x)Calculate harmonic mean for rates or ratios.Percentage Error Calculatorpercentage error = |measured − true| ÷ true × 100Calculate percentage error from measured and true values.Proportion Calculatorx = b × c ÷ aSolve a proportion of the form a/b = c/x.Nth Root Calculatorresult = value^(1/root)Calculate the nth root of a number.Significant Figures Calculatorrounded value = value rounded to significant figuresRound a number to a chosen number of significant figures.Weighted Average Calculatorweighted average = sum(value × weight) ÷ sum(weights)Calculate a weighted average from values and weights.Linear Interpolation Calculatory = y1 + (x − x1)(y2 − y1)/(x2 − x1)Estimate a value between two known points using linear interpolation.Exponential Growth Calculatorfuture value = initial × (1 + rate)^periodsCalculate exponential growth over time.Decimal to Percent Calculatorpercent = decimal × 100Convert a decimal into a percentage.Ratio to Percentage Calculatorpercentage = part ÷ whole × 100Convert a part-to-whole ratio into a percentage.Inverse Percentage Calculatororiginal = final ÷ (1 + percent/100)Find the original value before a percentage increase or decrease.Density Calculatordensity = mass ÷ volumeCalculate density, mass, or volume relationship.Hex to Decimal Calculatordecimal = base-16 valueConvert a hexadecimal number to decimal.Roman Numerals CalculatorRoman numerals are built from thousands, hundreds, tens, and onesConvert a number to Roman numerals.Binary Calculatorparse binary values, apply arithmetic, convert result back to binaryAdd, subtract, multiply, or divide binary numbers and show decimal equivalents.Matrix Calculatordeterminant = ad − bc; inverse exists when determinant is not zeroCalculate 2×2 matrix determinant and inverse helper values.Hexadecimal Calculatorconvert hex to decimal, apply operation, convert result to hexAdd, subtract, multiply, or divide hexadecimal numbers.Base Converterparse number in source base and output destination baseConvert a number between bases from 2 to 36.Determinant Calculator2×2 determinant = ad − bc; 3×3 uses rule of SarrusCalculate a 2×2 or 3×3 matrix determinant.Inverse Matrix Calculatorinverse = 1/(ad−bc) × [[d,-b],[-c,a]]Calculate the inverse of a 2×2 matrix.Complex Number Calculatorcomplex arithmetic using (a+bi) and (c+di)Add, subtract, multiply, or divide two complex numbers.Exponent Calculatorresult = base^exponentCalculate a number raised to a power.Number to Words Calculatorconverts a whole number into grouped English wordsConvert a number into English words for checks, invoices, and writing.Slope Intercept Calculatorb = y − mx; equation y = mx + bFind slope-intercept form from slope and a point.Distance Formula Calculatordistance = √((x2 − x1)² + (y2 − y1)²)Calculate the distance between two coordinate points.Circle Area Calculatorarea = πr²; circumference = 2πrCalculate the area and circumference of a circle from radius.Annular Ring Area Calculatorring area = π(R² − r²)Calculate the area of a ring shape from outer and inner radius.Cylinder Volume Calculatorvolume = πr²hCalculate cylinder volume and surface area from radius and height.Cone Volume Calculatorvolume = πr²h ÷ 3Calculate cone volume from radius and height.Sphere Volume Calculatorvolume = 4/3 × πr³; surface area = 4πr²Calculate sphere volume and surface area from radius.Right Triangle Calculatorhypotenuse = √(a² + b²); area = ab ÷ 2Calculate hypotenuse, area, and perimeter from two legs of a right triangle.Law of Sines Calculatorb = a × sin(B) ÷ sin(A)Use the law of sines to estimate a missing side from a known side and two angles.Law of Cosines Calculatorc² = a² + b² − 2ab cos(C)Calculate the third side of a triangle from two sides and the included angle.Expected Value Calculatorexpected value = sum(outcome × probability)Calculate expected value from outcomes and probabilities.Confidence Interval CalculatorCI = mean ± z × sd ÷ √nEstimate a confidence interval for a mean from sample mean, standard deviation, sample size, and z-score.Margin of Error CalculatorMOE = z × √(p(1−p)/n) × 100Calculate margin of error for a proportion from z-score, proportion, and sample size.Logarithm Calculatorlog base b of x = ln(x) ÷ ln(b)Calculate logarithm of a number using a custom base.Scientific Notation Calculatorscientific notation = coefficient × 10^exponentConvert a number to scientific notation.Fraction to Percent Calculatorpercent = numerator ÷ denominator × 100Convert a fraction into a percentage.Percent to Fraction Calculatorfraction = percent ÷ 100, then simplifyConvert a percent into a simplified fraction.Mixed Number to Decimal Calculatordecimal = whole + numerator ÷ denominatorConvert a mixed number into a decimal.Decimal to Mixed Number Calculatorwhole = floor(decimal); fraction = decimal remainder simplifiedConvert a decimal into a simplified mixed number.Prime Factorization Calculatordivide by prime factors until fully reducedFind the prime factorization of a whole number.Simplifying Fractions Calculatordivide numerator and denominator by their GCDReduce a fraction to its simplest form.Equivalent Fractions Calculatorequivalent fraction = numerator × multiplier over denominator × multiplierGenerate equivalent fractions for a given fraction.Mixed Number Calculatorconvert mixed numbers to improper fractions, calculate, then simplifyAdd, subtract, multiply, or divide two mixed numbers.Integer Calculatorstandard integer arithmeticCalculate integer addition, subtraction, multiplication, division, and remainder.Mean Calculatormean = sum of values ÷ countCalculate the arithmetic mean of a list of numbers.Median Calculatorsort values; median is middle value or average of two middle valuesCalculate the median middle value of a list of numbers.Mode Calculatormode = value with highest frequencyFind the most frequent value in a list of numbers.Range Calculatorrange = maximum value − minimum valueCalculate the range of a set of numbers.Interquartile Range CalculatorIQR = Q3 − Q1 after sorting valuesCalculate Q1, Q3, and interquartile range.Standard Form to Slope Intercept Calculatory = (-A/B)x + C/BConvert Ax + By = C into y = mx + b form.Point Slope Form Calculatory − y₁ = m(x − x₁)Create point-slope form from a point and slope.Cube Root Calculatorcube root = number^(1/3)Calculate the cube root of a number.Square Root Simplifier Calculator√n = outside × √inside after removing perfect square factorsSimplify square roots by factoring out perfect squares.Polynomial Degree Calculatordegree = highest exponent with nonzero coefficientFind the degree of a polynomial from its exponents.Arithmetic Sequence Calculatoraₙ = a₁ + (n − 1)d; sum = n(a₁ + aₙ)/2Calculate terms and sums for an arithmetic sequence.Geometric Sequence Calculatoraₙ = a₁ × r^(n−1); sum = a₁(rⁿ − 1)/(r − 1)Calculate terms and sums for a geometric sequence.Sum of Series Calculatorarithmetic sum or geometric sum depending on selected typeCalculate the sum of an arithmetic or geometric series.Percentage Point Calculatorpercentage points = new percent − old percentCalculate percentage point difference between two percentages.Percent Error Calculatorpercent error = |experimental − accepted| ÷ |accepted| × 100Calculate percent error between an experimental value and an accepted value.Relative Error Calculatorrelative error = |measured − true| ÷ |true|Calculate relative error and percent relative error.

Health

BMI CalculatorBMI = weight kg ÷ height m²Calculate body mass index from height and weight.Calorie CalculatorBMR × activity multiplierEstimate daily calories using the Mifflin-St Jeor equation.Pregnancy Due Date Calculatordue date = LMP + 280 daysEstimate due date from last menstrual period.Body Fat Calculatorbody fat ≈ 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4Estimate body fat percentage using a simple BMI-based method.Ideal Weight CalculatorDevine formula adjusted from 5 feet baselineEstimate ideal body weight using height.Water Intake Calculatorwater ≈ 35ml per kg + activity adjustmentEstimate daily water intake from body weight.BMR CalculatorMifflin-St Jeor BMR equationEstimate basal metabolic rate using weight, height, age, and sex.TDEE CalculatorTDEE = BMR × activity multiplierEstimate total daily energy expenditure from BMR and activity level.Macro Calculatorgrams = calories × macro % ÷ calories per gramSplit daily calories into protein, carbs, and fat targets.Protein Calculatorprotein target = weight × grams per kgEstimate daily protein target from body weight and grams per kg.Calories Burned Calculatorcalories = MET × 3.5 × weight ÷ 200 × minutesEstimate calories burned using MET, body weight, and duration.Target Heart Rate Calculatortarget zone = (220 − age) × intensityEstimate target heart rate zone from age and intensity.Sleep Calculatorwake time = bedtime + cycles × 90 minutesEstimate wake-up or bedtime options based on 90-minute sleep cycles.BMI Prime CalculatorBMI Prime = BMI ÷ 25Calculate BMI Prime relative to the upper normal BMI limit.Waist to Height Ratio Calculatorratio = waist ÷ heightCalculate waist-to-height ratio.One Rep Max Calculator1RM ≈ weight × (1 + reps ÷ 30)Estimate one-rep max from lifted weight and reps.Heart Rate Zone Calculatormax heart rate ≈ 220 − age; zones are percentages of maxEstimate training heart-rate zones from age.Pregnancy Week Calculatorpregnancy week = days since LMP ÷ 7Estimate pregnancy week from last menstrual period date.Ideal Body Weight CalculatorDevine estimate based on inches over 5 feetEstimate ideal body weight using height and sex.Army Body Fat Calculatorbody fat estimate using tape-measure circumference methodEstimate body fat using neck, waist, height, and sex inputs.BMI Imperial CalculatorBMI = 703 × weight(lb) ÷ height(in)^2Calculate BMI using pounds and inches.Steps to Miles Calculatormiles = steps × stride length ÷ 5280Convert step count into estimated miles.Waist to Hip Ratio Calculatorwaist-to-hip ratio = waist ÷ hipCalculate waist-to-hip ratio from body measurements.Fat Intake Calculatorfat grams = calories × percent ÷ 100 ÷ 9Estimate daily fat grams from calories and fat percentage.Carbohydrate Intake Calculatorcarb grams = calories × percent ÷ 100 ÷ 4Estimate daily carbohydrate grams from calories and carb percentage.Running Calorie Calculatorcalories ≈ weight kg × distance km × 1.036Estimate calories burned while running from weight and distance.Walking Calorie Calculatorcalories ≈ weight kg × distance km × 0.53Estimate calories burned while walking from weight and distance.Weight Loss Calculatordaily calorie deficit ≈ pounds to lose × 3500 ÷ daysEstimate calorie deficit needed to lose a target amount of weight.Calorie Deficit Calculatorweekly weight loss ≈ daily deficit × 7 ÷ 3500Estimate weekly weight loss from a daily calorie deficit.Lean Body Mass Calculatorlean body mass = weight × (1 − body fat %)Estimate lean body mass from weight and body fat percentage.Pace to Speed Calculatorspeed mph = 60 ÷ pace minutesConvert running pace per mile into speed in miles per hour.VO2 Max CalculatorVO2 max ≈ 15.3 × max heart rate ÷ resting heart rateEstimate VO2 max from resting and maximum heart rate using a common formula.Calories Per Meal Calculatorcalories per eating event = daily calories ÷ total meals/snacksSplit daily calories across meals and snacks.Macro Calories Calculatorcalories = protein×4 + carbs×4 + fat×9Calculate calories from grams of protein, carbs, and fat.Body Water Calculatorbody water = weight × percentageEstimate total body water from body weight and body water percentage.Target Weight Date Calculatorweeks = weight difference ÷ weekly changeEstimate time to reach a target weight from weekly change.Walking Pace Calculatorpace = time ÷ distanceCalculate walking pace and speed from distance and time.How Long to Walk a Mile Calculatorminutes per mile = 60 ÷ speed mphEstimate time to walk one mile from walking speed.How Many Steps in a Mile Calculatorsteps per mile = 63,360 ÷ stride lengthEstimate steps per mile from stride length.Kilojoules to Calories CalculatorCalories = kJ ÷ 4.184Convert kilojoules to food Calories.Miles to Steps Calculatorsteps = miles × steps per mileEstimate steps from miles and steps per mile.Sobriety Calculatordays sober = today − start dateCalculate days since a sobriety start date.Steps to Calories Calculatorcalories = steps × calories per stepEstimate calories burned from steps and calories per step.Steps to Km Calculatorkm = steps × stride meters ÷ 1000Convert steps to kilometers using stride length.WHR CalculatorWHR = waist ÷ hipCalculate waist-to-hip ratio from waist and hip measurements.Body Surface Area CalculatorBSA = sqrt(height × weight ÷ 3600)Estimate body surface area from height and weight.Race Time Predictor Calculatortarget time = known time × (target distance ÷ known distance)^1.06Predict running race time from a known distance and time using the Riegel formula.Caffeine Calculatortotal caffeine = mg per serving × servingsEstimate total caffeine intake from drinks or servings.Marathon Pace Calculatorpace = total time ÷ 42.195 km and ÷ 26.2188 milesCalculate marathon pace from target finish time.Pace Per Kilometer Calculatorpace per km = total time ÷ distanceCalculate running pace per kilometer from distance and time.Corrected Calcium Calculatorcorrected calcium = calcium + 0.8 × (4 − albumin)Estimate albumin-corrected calcium using a common clinical formula.Meal Calorie Calculatormeal calories = sum of item caloriesAdd food item calories to estimate total meal calories.Pregnancy Month Calculatormonth estimate = week ÷ 4.345Estimate pregnancy month from pregnancy week for general planning.Due Date by Conception Date Calculatorestimated due date = conception date + 266 daysEstimate due date from conception date.Sleep Debt Calculatorsleep debt = (needed − actual) × daysEstimate weekly sleep debt from needed sleep and actual sleep.Hydration by Weight Calculatordaily water = weight × mL per kgEstimate daily water intake from body weight using a simple ml/kg rule.Macro Split Calculatorprotein/carbs grams = calories × percent ÷ 4; fat grams = calories × percent ÷ 9Convert calorie targets and macro percentages into grams of protein, carbs, and fat.Target Pace Calculatorpace = total time ÷ distanceCalculate target pace from goal time and race distance.Resting Heart Rate Zone CalculatorHRR = max HR − resting HR; zone = resting HR + HRR × intensityEstimate training zones using age and resting heart rate with the heart-rate reserve method.Body Frame Size Calculatorframe estimate uses height-to-wrist ratioEstimate body frame size from wrist circumference and height.Daily Water Intake Calculatorwater = weight × mL per kg + activity adjustmentEstimate daily water intake from body weight and activity time.Body Fat Navy CalculatorNavy body fat estimate from height, neck, waist, and hip measurementsEstimate body fat percentage using the U.S. Navy-style circumference method.Ideal Running Weight Calculatorlean mass = weight × (1 − body fat); target weight = lean mass ÷ (1 − target body fat)Estimate a running weight target from current weight and target body fat percentage.Protein Calorie Calculatorprotein calories = grams × 4; percent = protein calories ÷ daily calories × 100Convert protein grams into calories and percentage of daily calories.Metabolic Age Calculatorsimple estimate compares BMR to reference BMR and adjusts ageEstimate metabolic age from BMR compared with an expected BMR reference.Walking Time Calculatortime hours = distance ÷ speedEstimate how long a walk will take from distance and walking speed.Running Time Calculatortime minutes = distance × paceEstimate running time from distance and pace.Cycling Speed Calculatorspeed = distance ÷ timeCalculate average cycling speed from ride distance and time.Swimming Pace Calculatorpace per 100m = total time ÷ distance × 100Calculate swimming pace per 100 meters from distance and total time.Walking Speed Calculatorspeed km/h = distance ÷ (minutes ÷ 60)Calculate walking speed from distance and time.Steps Per Minute Calculatorsteps per minute = steps ÷ minutesCalculate walking or running cadence from total steps and time.Stride Length Calculatorstride length = distance ÷ stepsEstimate average stride length from distance and step count.Max Heart Rate Calculatormax heart rate ≈ 220 − age; Tanaka estimate = 208 − 0.7 × ageEstimate maximum heart rate from age using common formulas.One Mile Walk Test CalculatorRockport estimate: VO2 max = 132.853 − 0.0769w − 0.3877a + 6.315s − 3.2649t − 0.1565hrEstimate VO2 max from a one-mile walk test using time, heart rate, age, sex, and weight.Cooper Test CalculatorVO2 max ≈ (distance meters − 504.9) ÷ 44.73Estimate VO2 max from distance covered in 12 minutes.Karvonen Heart Rate Calculatortarget HR = ((max HR − resting HR) × intensity) + resting HRCalculate training heart-rate targets using resting heart rate and intensity.Maintenance Calorie Calculatormaintenance calories = BMR × activity multiplierEstimate daily maintenance calories from BMR and activity multiplier.Protein Per Meal Calculatorprotein per meal = daily target ÷ mealsSplit a daily protein target across meals.Sleep Time Calculatorbedtime = wake time − cycles × 90 minutesCalculate bedtime or wake time using 90-minute sleep cycles.Sleep Duration Calculatorsleep duration = wake time − bedtime, crossing midnight if neededCalculate sleep duration from bedtime and wake time.Body Adiposity Index CalculatorBAI = hip cm ÷ height m^1.5 − 18Estimate body adiposity index from hip circumference and height.Body Roundness Index CalculatorBRI ≈ 364.2 − 365.5 × sqrt(1 − (waist/(2π))² ÷ (0.5×height)²)Estimate body roundness index from waist circumference and height.Resting Metabolic Rate CalculatorRMR estimate uses the Mifflin-St Jeor equationEstimate resting metabolic rate from weight, height, age, and sex.Ideal Weight Range Calculatorweight range = BMI × height² for BMI 18.5–24.9Estimate a general healthy weight range from height using BMI 18.5 to 24.9.Hydration by Activity Calculatordaily water = base + exercise hours × extra liters/hourEstimate extra water needs from exercise duration and sweat rate.Weight Change Calculatorchange = current − start; percent = change ÷ start × 100Calculate weight change amount and percentage between two weights.Net Carbs Calculatornet carbs = total carbs − fiber − sugar alcoholsEstimate net carbohydrates from total carbs, fiber, and sugar alcohols.Fiber Calculatorfiber target = calories ÷ 1000 × grams per 1000 caloriesEstimate daily fiber target from calories or a direct grams-per-day goal.Gram to Calorie Calculatorcalories = grams × macro calorie factorConvert macro grams to calories using protein, carb, fat, or alcohol factors.Calorie to Gram Calculatorgrams = calories ÷ macro calorie factorConvert calories to macro grams using protein, carb, fat, or alcohol factors.

Date & Time

Age Calculatorage = difference between today and birth dateCalculate exact age from date of birth.Date Calculatorresult date = start date + daysAdd or subtract days from a date.Days Between Dates Calculatordays = end date − start dateCount days between two dates.Time Duration Calculatorduration = end time − start timeCalculate the duration between two times.Countdown Calculatordays remaining = target date − todayCalculate days remaining until a future date.Work Hours Calculatorwork hours = end time − start time − breakCalculate total work hours from start time, end time, and break length.Time Zone Difference Calculatordifference = to offset − from offsetCalculate the hour difference between two UTC offsets.Due Date Countdown Calculatordays left = due date − todayCalculate days remaining until a due date.Age Difference Calculatorage difference = absolute days between datesCalculate the difference between two birth dates.Chronological Age Calculatorchronological age = target date − birth dateCalculate chronological age from birth date to a target date.Days From Today Calculatordate = today + daysFind the date a number of days from today.Days Until Calculatordays until = target date − todayCalculate how many days remain until a date.Generation Calculatorgeneration based on common birth-year rangesEstimate generation label from birth year.Birthday Calculatornext birthday = next occurrence of birth month/dayCalculate days until next birthday and approximate age.Business Days Between Dates Calculatorbusiness days = weekdays between start and end datesCount weekdays between two dates, excluding Saturdays and Sundays.Add Business Days Calculatortarget date = start date plus weekdays, skipping Saturday and SundayAdd business days to a start date while skipping weekends.Week Number CalculatorISO week number is calculated from the Thursday of the weekFind the ISO week number for a date.Minutes Between Times Calculatorminutes = end − start − break; adds 24h if end is next dayCalculate minutes and hours between two times.Decimal Hours to Hours Minutes Calculatorhours = floor(decimal); minutes = decimal remainder × 60Convert decimal hours into hours and minutes for payroll or time tracking.Baby Age Calculatorage = today − birth dateCalculate baby age in days, weeks, and months from birth date.Paycheck Date Calculatorfuture paycheck date = start date + period days × checks aheadEstimate future paycheck dates from a start date and pay frequency.Hours Until Calculatorhours until = target datetime − nowCalculate hours until a future date and time.Weeks Between Dates Calculatorweeks = days between dates ÷ 7Calculate weeks and days between two dates.Months Between Dates Calculatormonths between dates estimated from calendar-day differenceCalculate approximate months and days between two dates.Days Since Date Calculatordays since = today − start dateCalculate how many days have passed since a selected date.Military Time Converter24-hour time = hour adjusted by AM/PM; minutes stay the sameConvert standard 12-hour time to 24-hour military time and back.

Construction

Converters

Business

Profit Margin Calculatormargin = (revenue − cost) ÷ revenue × 100Calculate gross profit and profit margin percentage.Markup Calculatormarkup = (price − cost) ÷ cost × 100Calculate markup percentage from cost and selling price.Freelance Rate Calculatorrate = (target + expenses) ÷ billable hoursEstimate an hourly freelance rate from income goals and billable hours.Invoice Total Calculatortotal = subtotal − discount + taxCalculate invoice subtotal, tax, discount, and final total.PayPal Fee Calculatorfee = amount × percent ÷ 100 + fixed feeEstimate PayPal-style transaction fees using a percentage plus fixed fee.Stripe Fee Calculatorfee = amount × percent ÷ 100 + fixed feeEstimate card processing fees using a percentage plus fixed fee.ROI CalculatorROI = (gain − cost) ÷ cost × 100Calculate return on investment percentage.CPM CalculatorCPM = cost ÷ impressions × 1000Calculate advertising cost per thousand impressions.CPC CalculatorCPC = cost ÷ clicksCalculate advertising cost per click.CTR CalculatorCTR = clicks ÷ impressions × 100Calculate click-through rate from clicks and impressions.Conversion Rate Calculatorconversion rate = conversions ÷ visitors × 100Calculate conversion rate from visitors and conversions.Break-Even Calculatorbreak-even units = fixed costs ÷ (price − variable cost)Calculate how many units you need to sell to break even.Commission Calculatorcommission = sales × commission rateCalculate commission earnings from sales and commission rate.Revenue Growth Calculatorgrowth = (current − previous) ÷ previous × 100Calculate revenue growth percentage between two periods.Customer Acquisition Cost CalculatorCAC = acquisition spend ÷ new customersCalculate CAC from marketing spend and new customers.LTV CalculatorLTV = AOV × purchase frequency × lifespanEstimate customer lifetime value from average order, purchase frequency, and lifespan.Churn Rate Calculatorchurn rate = lost customers ÷ starting customers × 100Calculate customer churn rate for a period.Meeting Cost Calculatormeeting cost = people × hourly rate × minutes ÷ 60Estimate the labor cost of a meeting.Gross Profit Calculatorgross profit = revenue − COGSCalculate gross profit from revenue and cost of goods sold.Net Profit Calculatornet profit = revenue − expensesCalculate net profit after expenses.Operating Margin Calculatoroperating margin = operating income ÷ revenue × 100Calculate operating margin from operating income and revenue.ARPU CalculatorARPU = revenue ÷ usersCalculate average revenue per user.Lead Conversion Calculatorlead conversion rate = customers ÷ leads × 100Calculate how many leads convert into customers.Email Open Rate Calculatoropen rate = opens ÷ delivered × 100Calculate email campaign open rate.Email Click Rate Calculatoremail click rate = clicks ÷ delivered × 100Calculate email click rate from clicks and delivered emails.ROAS CalculatorROAS = revenue ÷ ad spendCalculate return on ad spend.Profit Per Unit Calculatorprofit per unit = selling price − unit costCalculate profit per item sold.Productivity Calculatorproductivity = output ÷ hoursCalculate output per hour or per worker.Burn Rate Calculatorburn rate = (starting cash − ending cash) ÷ monthsCalculate monthly cash burn.Runway Calculatorrunway = cash ÷ monthly burnEstimate how many months cash will last.Time Card Calculatorworked hours = end − start − breaksCalculate total work hours from start time, end time, and break minutes.Depreciation Calculatorannual depreciation = (cost − salvage value) ÷ useful lifeEstimate straight-line annual depreciation.Inventory Turnover Calculatorinventory turnover = COGS ÷ average inventoryCalculate inventory turnover from cost of goods sold and average inventory.EBITDA Margin CalculatorEBITDA margin = EBITDA ÷ revenue × 100Calculate EBITDA margin from EBITDA and revenue.Retention Rate Calculatorretention rate = (end customers − new customers) ÷ start customers × 100Calculate customer retention rate over a period.Email Conversion Rate Calculatoremail conversion rate = conversions ÷ delivered emails × 100Calculate email conversion rate from conversions and delivered emails.Bounce Rate Calculatorbounce rate = bounces ÷ visits × 100Calculate bounce rate from bounced visits and total visits.LTV CAC Ratio CalculatorLTV:CAC ratio = LTV ÷ CACCalculate the ratio between customer lifetime value and customer acquisition cost.MRR CalculatorMRR = customers × average monthly revenueCalculate monthly recurring revenue from customers and average subscription price.ARR CalculatorARR = MRR × 12Calculate annual recurring revenue from monthly recurring revenue.MRR Growth CalculatorMRR growth = (ending MRR − starting MRR) ÷ starting MRR × 100Calculate monthly recurring revenue growth from starting and ending MRR.Revenue Churn Calculatorrevenue churn = lost MRR ÷ starting MRR × 100Calculate revenue churn rate from lost recurring revenue and starting MRR.Contribution Margin Calculatorcontribution margin = price − variable costCalculate contribution margin per unit and contribution margin ratio.Break Even Revenue Calculatorbreak-even revenue = fixed costs ÷ contribution margin ratioCalculate revenue needed to break even from fixed costs and contribution margin ratio.Average Order Value CalculatorAOV = revenue ÷ ordersCalculate average order value from revenue and number of orders.Cart Abandonment Rate Calculatorabandonment rate = (carts − orders) ÷ carts × 100Calculate cart abandonment rate from carts created and completed purchases.Refund Rate Calculatorrefund rate = refunds ÷ orders × 100Calculate refund rate from refunded orders and total orders.Debt Service Coverage Ratio CalculatorDSCR = NOI ÷ debt serviceCalculate DSCR from net operating income and annual debt service.Net Revenue Retention CalculatorNRR = (start + expansion − contraction − churn) ÷ start × 100Calculate NRR from starting MRR, expansion, contraction, and churn.Gross Revenue Retention CalculatorGRR = (start − contraction − churn) ÷ start × 100Calculate GRR excluding expansion revenue.Payback Period Calculatorpayback period = investment ÷ annual cash flowCalculate how long it takes to recover an investment from annual cash flow.Average Revenue Per Account CalculatorARPA = revenue ÷ accountsCalculate ARPA from recurring revenue and accounts.Cost Per Lead CalculatorCPL = campaign cost ÷ leadsCalculate marketing cost per lead.Cost Per Acquisition CalculatorCPA = campaign cost ÷ acquired customersCalculate acquisition cost from spend and acquired customers.Gross Merchandise Value CalculatorGMV = orders × average order valueCalculate GMV from order count and average order value.Marketplace Fee Calculatorfee = sale × fee% + fixed feeEstimate marketplace fee and seller payout.Shipping Profit Calculatorshipping profit = charged − actual cost − packagingCalculate profit or loss from shipping charged vs shipping cost.Profit Per Order Calculatorprofit per order = revenue − costsCalculate profit per order after product cost, fees, shipping, and ads.Break Even ROAS Calculatorbreak-even ROAS = 1 ÷ marginCalculate ROAS needed to break even from gross margin.Quick Ratio Calculatorquick ratio = (cash + receivables) ÷ current liabilitiesCalculate quick ratio from liquid assets and current liabilities.Current Ratio Calculatorcurrent ratio = current assets ÷ current liabilitiesCalculate current ratio from current assets and current liabilities.Cash Conversion Cycle Calculatorcash conversion cycle = DIO + DSO − DPOCalculate cash conversion cycle from inventory, receivable, and payable days.Net Promoter Score CalculatorNPS = % promoters − % detractorsCalculate NPS from promoters, passives, and detractors.Inventory Days Calculatordays inventory = average inventory ÷ COGS × period daysEstimate days of inventory on hand from average inventory and cost of goods sold.Discounted Cash Flow CalculatorDCF = sum(cash flow ÷ (1+r)^t) + terminal value ÷ (1+r)^nEstimate present value from future cash flows and a discount rate.Gross Margin Return on Investment CalculatorGMROI = gross margin dollars ÷ average inventory costCalculate GMROI from gross margin dollars and average inventory cost.Profit Percentage Calculatorprofit percentage = (price − cost) ÷ cost × 100Calculate profit percentage from cost and selling price.Operating Profit Calculatoroperating profit = revenue − COGS − operating expensesCalculate operating profit from revenue, COGS, and operating expenses.Revenue Per Employee Calculatorrevenue per employee = revenue ÷ employeesCalculate revenue per employee for productivity benchmarking.Burn Multiple Calculatorburn multiple = net burn ÷ net new ARREstimate startup burn multiple from net burn and net new ARR.Customer Churn Cost Calculatorlost revenue = customers lost × ARPU × monthsEstimate monthly revenue lost from customer churn.Employee Turnover Rate Calculatorturnover rate = departures ÷ average employees × 100Calculate employee turnover rate for a period.Absenteeism Rate Calculatorabsenteeism rate = absent days ÷ scheduled workdays × 100Calculate absenteeism rate from lost workdays and scheduled workdays.Utilization Rate Calculatorutilization rate = billable hours ÷ available hours × 100Calculate utilization rate from billable hours and available hours.Billable Hours Calculatornet billable revenue = rate × billable hours − expensesEstimate billable revenue from hourly rate, billable hours, and non-billable time.Revenue Run Rate Calculatorannual run rate = period revenue ÷ months × 12Annualize current revenue to estimate revenue run rate.Labor Cost Percentage Calculatorlabor cost percentage = labor cost ÷ revenue × 100Calculate labor cost as a percentage of revenue.Food Cost Percentage Calculatorfood cost percentage = food cost ÷ food sales × 100Calculate restaurant food cost percentage from food cost and food sales.Repeat Purchase Rate Calculatorrepeat purchase rate = repeat customers ÷ total customers × 100Calculate repeat purchase rate from repeat customers and total customers.Shipping Cost Calculatorshipping cost = packages × (base fee + weight × rate)Estimate shipping cost from weight, distance rate, base fee, and package count.Dimensional Weight Calculatordimensional weight = length × width × height ÷ divisorCalculate dimensional shipping weight from package dimensions and divisor.Debt to Equity Ratio Calculatordebt-to-equity ratio = total debt ÷ total equityCalculate debt-to-equity ratio from total liabilities and shareholder equity.Working Capital Calculatorworking capital = current assets − current liabilitiesCalculate working capital from current assets and current liabilities.Marketing Efficiency Ratio CalculatorMER = revenue ÷ marketing spendCalculate MER from revenue and marketing spend.Conversion Value Calculatorconversion value = conversions × average valueEstimate total conversion value from conversions and average value per conversion.Return on Sales Calculatorreturn on sales = operating profit ÷ net sales × 100Calculate return on sales from operating profit and net sales.Net Working Capital Ratio Calculatorworking capital ratio = current assets ÷ current liabilitiesCalculate current ratio style working capital coverage from current assets and current liabilities.Inventory Carrying Cost Calculatorcarrying cost % = annual carrying costs ÷ average inventory value × 100Estimate inventory carrying cost percentage from storage, insurance, capital, and service costs.Accounts Receivable Turnover CalculatorAR turnover = net credit sales ÷ average accounts receivableCalculate accounts receivable turnover from net credit sales and average receivables.Accounts Payable Turnover CalculatorAP turnover = purchases ÷ average accounts payableCalculate accounts payable turnover from supplier purchases and average accounts payable.Units Per Transaction Calculatorunits per transaction = units sold ÷ ordersCalculate average units per transaction from units sold and orders.Revenue Per Visitor Calculatorrevenue per visitor = revenue ÷ visitorsCalculate revenue per visitor for ecommerce or website traffic.Return Rate Calculatorreturn rate = returned orders ÷ total orders × 100Calculate product return rate from returned orders and total orders.Chargeback Rate Calculatorchargeback rate = chargebacks ÷ transactions × 100Calculate chargeback rate from chargebacks and total transactions.Net Sales Calculatornet sales = gross sales − returns − discounts − allowancesCalculate net sales after returns, discounts, and allowances.Sell Through Rate Calculatorsell-through rate = units sold ÷ starting inventory × 100Calculate sell-through rate from units sold and starting inventory.Stockout Rate Calculatorstockout rate = stockouts ÷ demand events × 100Calculate stockout rate from stockout events and total demand events.Support Cost Per Ticket Calculatorcost per ticket = support cost ÷ tickets handledCalculate customer support cost per ticket.Commercial Lease Calculatorannual rent = square feet × rate; monthly = annual ÷ 12Estimate monthly and annual commercial rent from square feet and rent per square foot.Break Even Sales Calculatorbreak-even sales = fixed costs ÷ gross marginCalculate the sales revenue needed to break even from fixed costs and gross margin.Cash Runway Calculatorrunway months = cash ÷ monthly burnEstimate how many months business cash will last at the current burn rate.Customer Lifetime Value CalculatorCLV = AOV × frequency × lifespan × gross marginEstimate customer lifetime value from average order value, purchase frequency, margin, and lifespan.Ecommerce Break Even ROAS Calculatorbreak-even ROAS = 1 ÷ contribution marginCalculate the ROAS needed to break even after gross margin and variable costs.Customer Acquisition Payback Calculatorpayback months = CAC ÷ monthly gross profitEstimate CAC payback period in months from CAC and monthly gross profit.Accounts Receivable Days CalculatorDSO = receivables ÷ credit sales × daysCalculate days sales outstanding from accounts receivable and credit sales.Accounts Payable Days CalculatorDPO = accounts payable ÷ COGS × daysCalculate days payable outstanding from accounts payable and cost of goods sold.Business Loan Calculatorpayment = P × r(1+r)^n ÷ ((1+r)^n − 1)Estimate business loan payment, total repayment, and total interest.

Education

Grade Calculatorfinal contribution = score × weight ÷ 100Calculate weighted grade from score and weight.GPA CalculatorGPA = grade points ÷ creditsCalculate GPA from total grade points and credits.GPA to Percentage Calculatorpercentage ≈ GPA ÷ scale × 100Convert GPA to an approximate percentage using a simple scale.Final Grade Calculatorneeded = (target − current × (1 − final weight)) ÷ final weightCalculate the final exam score needed to reach a target course grade.Weighted Grade Calculatorweighted grade = sum(grade × weight) ÷ total weightCalculate a weighted grade from three grade/weight pairs.Exam Score Needed Calculatorneeded final = (target − current×(1−weight)) ÷ weightCalculate the score needed on a final exam to reach a target grade.University Grade Calculatorweighted grade = sum(mark × credits) ÷ total creditsCalculate weighted university grade from marks and credits.Class Average Calculatorclass average = total scores ÷ number of scoresCalculate the average score for a class or group.Test Grade Calculatorgrade percent = earned points ÷ total points × 100Calculate test percentage and letter-style score from points earned.Molarity Calculatormolarity = moles ÷ litersCalculate molarity from moles of solute and solution volume.Molar Mass Calculatormolar mass = sum(atom count × atomic mass)Estimate molar mass from common atom counts for C, H, O, N, Na, and Cl.Dilution CalculatorC2 = C1 × V1 ÷ V2Calculate final concentration after dilution.Concentration Calculatorconcentration = mass ÷ volumeCalculate mass concentration from solute mass and solution volume.pH CalculatorpH = −log10([H+])Calculate pH from hydrogen ion concentration.

Engineering

Ohm’s Law CalculatorV = I × R; P = V × ICalculate voltage, current, resistance, and power using Ohm’s law.Voltage Drop Calculatorvoltage drop = 2 × length × current × resistance ÷ 1000Estimate voltage drop from current, wire resistance, and cable length.Resistor Calculatorresistance = voltage ÷ currentCalculate resistance from voltage and current.Bandwidth Calculatortime seconds = size GB × 8192 ÷ MbpsEstimate data transfer time from file size and bandwidth.Data Transfer Calculatordata GB = speed Mbps × seconds ÷ 8192Calculate data transferred from speed and time.Resistor Color Code Calculatorresistance = two-digit number × 10^multiplierCalculate resistance from digit bands, multiplier, and tolerance.Resistor Parallel CalculatorR = 1 ÷ (1/R1 + 1/R2)Calculate equivalent resistance for two resistors in parallel.Resistor Series Calculatorseries resistance = sum of resistorsCalculate equivalent resistance for resistors in series.Capacitor Charge Calculatorcharge = C × V; energy = 1/2 × C × V²Calculate capacitor charge and stored energy.Wavelength Frequency Calculatorwavelength = speed ÷ frequencyCalculate wavelength from wave speed and frequency.Kinetic Energy CalculatorKE = 1/2 × mass × velocity²Calculate kinetic energy from mass and velocity.Potential Energy CalculatorPE = mass × gravity × heightCalculate gravitational potential energy.Force Calculatorforce = mass × accelerationCalculate force from mass and acceleration.Work Calculatorwork = force × distanceCalculate mechanical work from force and distance.Acceleration Calculatoracceleration = (final velocity − initial velocity) ÷ timeCalculate acceleration from velocity change and time.Angular Velocity Calculatorrad/s = RPM × 2π ÷ 60Convert RPM to angular velocity in radians per second.

Everyday

Fuel Cost Calculatorcost = distance × L/100km ÷ 100 × priceEstimate trip fuel cost from distance, efficiency, and fuel price.Electricity Cost Calculatorcost = watts ÷ 1000 × hours × priceEstimate electricity cost from watts, hours, and price per kWh.Pace Calculatorpace = total minutes ÷ distanceCalculate pace per kilometer from distance and time.Download Time Calculatortime seconds = file gigabits ÷ MbpsEstimate download time from file size and internet speed.Fuel Efficiency Calculatorfuel efficiency = distance ÷ fuel usedCalculate miles per gallon or kilometers per liter from distance and fuel used.Gas Cost Per Mile Calculatorcost per mile = gas price ÷ MPGEstimate fuel cost per mile from fuel price and vehicle MPG.Reading Time Calculatorreading time = words ÷ words per minuteEstimate reading time from word count and reading speed.Typing Speed CalculatorWPM = words ÷ minutesCalculate typing speed in words per minute.Heat Pump Savings Calculatorsavings = current cost − heat pump kWh × electric rateEstimate potential home energy savings from switching heating usage to a heat pump.Water Bill Calculatorbill = usage × rate + fixed chargeEstimate a water bill from usage, rate, and fixed charges.Roman Numeral Date Converterconvert month, day, and year numbers into Roman numeralsConvert a calendar date into a Roman numeral date format.Average Speed Calculatoraverage speed = distance ÷ timeCalculate average speed from distance and time.Speed Distance Time Calculatortime = distance ÷ speedSolve for travel time from distance and speed.

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