How to Calculate Your BMI

BMI equals your weight in kilograms divided by your height in metres squared (kg/m²). A BMI calculator does this instantly and shows which category the result falls into.

Last updated: 2026-07-17

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The formula

Metric: BMI = weight (kg) ÷ height (m)². Someone 1.75m tall weighing 70kg has a BMI of 70 ÷ (1.75 × 1.75) ≈ 22.9.
Imperial: BMI = 703 × weight (lb) ÷ height (in)².

Do it instantly

Enter your height and weight in the BMI Calculator — it works in metric or imperial and shows your category.

What the numbers mean

Under 18.5 — underweight
18.5–24.9 — healthy range
25–29.9 — overweight
30+ — obese

The important caveat

BMI is a quick population-level screen, not a diagnosis. It doesn't distinguish muscle from fat, so athletes can read as "overweight", and it doesn't account for age, sex or body composition. Treat it as one rough indicator and consult a professional for real health advice. To estimate daily calorie needs, use the Calorie Calculator.

Private

Your height and weight are used only in your browser.

Frequently asked questions

What is a healthy BMI range?

18.5 to 24.9 is generally considered the healthy range, but BMI is a rough screen and doesn't account for muscle, age or body composition.

Is BMI accurate for athletes?

Not really — muscle weighs more than fat, so muscular people can register as 'overweight' despite low body fat. BMI is a general indicator, not a diagnosis.

Tools used in this guide

BMI Calculator

Calculate body mass index in metric or imperial.

Calorie Calculator

Estimate daily calorie needs (BMR and TDEE).