♥ Health calculator

BMI Calculator

Calculate body mass index from height and weight. Enter your values below to calculate in the browser and review the formula, example, and cautions on the same page.

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BMI Calculator

Enter the values you know. The result updates in your browser and stays separate from the notes and examples.

Use realistic values. Invalid, missing, or impossible inputs will show a friendly warning instead of a broken result.

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The live calculator needs JavaScript to recalculate custom inputs, but this page still includes the calculator form, formula, worked example, and limitations.

Formula: BMI = weight kg ÷ height m²

Inputs	70 kg and 175 cm
BMI	22.86
Category	Normal BMI range for most adults

Estimate only. This result is not medical advice and does not replace a clinician, dietitian, trainer, or qualified health professional. Health formulas can miss individual context.

ResultEnter values, then calculate.Your output appears here after calculation.

Health estimate: Estimate only. This result is not medical advice and does not replace a clinician, dietitian, trainer, or qualified health professional. Health formulas can miss individual context.

Reviewed estimate context

Health estimate limits

What this result is

BMI Calculator gives a browser-calculated estimate from the inputs you enter and the formula displayed on this page.

What can change it

Use the result as a general estimate only. Ask a qualified health professional before changing medication, diagnosis, diet, training, or treatment decisions.

Formula transparency

Formula source type: standard public screening or fitness formula shown on this page. Last review marker: 2026-06-28. Report unclear formulas through the contact page.

Calculator modes and related uses

Metric BMIUse height and weight to estimate BMI.

Imperial BMIUse BMI Imperial for feet, inches, and pounds.

Body composition contextCompare with body fat, ideal weight, and lean body mass calculators.

Health cautionUse BMI as a screening estimate, not a diagnosis.

Recent results on this device

Calculate once to save a local result on this device.

Formula

BMI = weight kg ÷ height m²

Uses: BMI = weight kg ÷ height m².

Steps

Enter the values using the units shown in the form.
Run the formula.
Check the result against the formula and worked example before using it elsewhere.

Examples

70kg and 175cm = BMI 22.86

Source-linked deep guide

BMI Calculator: weight compared with height squared

BMI compares body weight with height. The BMI calculator gives a screening number, not a personal diagnosis.

Think of carrying a backpack. The same backpack feels different on a small child than on a tall adult. BMI tries to compare weight with body size.

Core Formula

BMI = Weight kgHeight m × Height m

Height is multiplied by itself because BMI compares weight with body size, not height alone.

BMI formula variables
Symbol	Meaning	Simple way to think about it
Weight kg	Body weight in kilograms	The amount being compared
Height m	Height in meters	The size measure
Height²	Height multiplied by itself	The body-size adjustment

Step-by-step example

Find BMI for a person who weighs 70 kg and is 1.75 m tall.

Start with the height: 1.75 m.
Square the height: 1.75 × 1.75 = 3.0625.
Divide weight by squared height: 70 ÷ 3.0625 = 22.86.
The BMI is about 22.9.

Adult BMI categories

CDC adult BMI categories
Category	BMI range	Plain meaning
Underweight	Below 18.5	Lower than the adult reference range
Healthy weight	18.5 to 24.9	Within the adult reference range
Overweight	25.0 to 29.9	Above the healthy adult range
Obesity	30.0 or higher	High adult BMI category

Common mistakes and edge cases

Do not enter centimeters as meters. Use 1.75 m, not 175 m.
Height cannot be zero. The calculator blocks zero height because division by zero is impossible.
BMI is not body-fat percentage. It does not measure muscle, bone density, or fat distribution directly.
Adult BMI is different from child BMI. Children and teens use age and sex percentiles.

Sources and accuracy notes

The CDC defines adult BMI as weight in kilograms divided by height in meters squared. The CDC also lists adult BMI categories for people age 20 and older. See CDC: Adult BMI categories and CDC: Adult BMI calculator.

Use BMI as a general screening estimate. It is not medical advice, and it cannot replace a qualified health professional.

FAQ

Is BMI a diagnosis?

No. BMI is a screening estimate and should not be treated as a diagnosis.

Why can BMI be misleading?

BMI does not distinguish muscle, fat, bone structure, or body composition.

What BMI ranges are commonly used?

Common adult BMI categories are under 18.5 for underweight, 18.5 to 24.9 for normal range, 25 to 29.9 for overweight, and 30 or higher for obesity. These are screening ranges, not diagnoses.

What calculator should I compare with BMI?

Body fat, waist-to-height, BMR, TDEE, and calorie calculators can add context that BMI alone cannot provide.

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