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Health

BMI Calculator - Body Mass Index

Work out your body mass index in seconds. Enter your weight and height in metric or imperial units and this free BMI calculator shows your BMI value, weight category and the healthy weight range for your height. Switch between the WHO international standard and the stricter Asian/Thai cut-offs, and see exactly where you sit on the BMI scale. Everything is calculated in your browser — nothing is uploaded.

kg
BMI classification

Asian populations face health risks at a lower BMI, so the normal range is stricter (18.5–22.9).

Your BMI will appear here

Enter your weight and height to calculate your BMI.

How to use

  1. Pick metric (kg / cm) or imperial (lb / ft-in) units.
  2. Enter your weight and height; height accepts centimetres or metres.
  3. Choose the WHO standard or Asian/Thai cut-offs for classification.
  4. Read your BMI value, category and healthy weight range instantly.
  5. Use the colour scale to see where your BMI falls, then copy the result.

Features

  • Metric and imperial units with feet-and-inches height entry
  • WHO international and Asian/Thai BMI cut-offs
  • Healthy weight range calculated for your exact height
  • Colour-coded BMI scale with a marker for your result
  • Copy your BMI summary in one click
  • 100% in-browser — your data never leaves your device

Frequently asked questions

How is BMI calculated?
BMI equals your weight in kilograms divided by your height in metres squared (kg/m²). For example, 65 kg at 1.70 m gives 65 ÷ (1.70 × 1.70) = 22.5. This calculator does the maths for you in metric or imperial units.
What is a healthy BMI range?
Under the WHO standard a BMI of 18.5–24.9 is normal, below 18.5 is underweight, 25–29.9 is overweight and 30 or more is obese. Asian/Thai cut-offs set the normal range at 18.5–22.9, with 23 and over counted as overweight.
Why do Asian and Thai BMI cut-offs differ from the WHO standard?
Research shows people of Asian descent can face higher risks of diabetes and heart disease at a lower BMI. Thailand and the WHO Asia-Pacific guidelines therefore treat a BMI of 23 and above as overweight, rather than 25.
Is BMI accurate for everyone?
BMI is a quick screening tool, not a diagnosis. It does not distinguish muscle from fat, so athletes may read as overweight, and it is not designed for children, pregnant women or the elderly. Use it as a guide and consult a doctor.
Is this BMI calculator free?
Yes. This BMI calculator is completely free, needs no sign-up, and runs entirely in your browser. Your weight and height are never sent to a server or stored anywhere.