BMI Calculator
Body mass index from height and weight, with the category it falls into.
How this calculator works
Body mass index is a quick screening figure comparing weight to height. It does not account for muscle mass, build or age, so treat it as one signal among many rather than a diagnosis.
Body mass index (BMI) is a quick screening figure that compares your weight to your height. It is widely used because it needs only two measurements and no equipment beyond a scale and a tape measure, and it gives a single number that falls into a standard category: underweight, normal weight, overweight, or obese. The BMI Calculator works out the index from your height and weight and shows which band it lands in.
BMI is a screening tool, not a diagnosis. It does not distinguish between muscle and fat, so a heavily muscled athlete can register as overweight despite being lean, and it says nothing about where fat is carried, which matters for health. Older adults, children, pregnant people and those with a very athletic or slight build should read the number with particular caution.
Use BMI as one signal among many — alongside waist measurement, blood pressure, energy levels and how you feel — rather than as a verdict on your health. If the result surprises or concerns you, a conversation with a healthcare professional is a better next step than acting on the number alone.
Everything runs in your browser as you type — nothing is stored or sent to a server. Results are estimates for general guidance and should not replace advice from a qualified professional.
Frequently asked questions
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered the normal weight range. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat and ignores fat distribution, age and build. Athletes, older adults, pregnant people and children should interpret the number with caution.
Should I rely on BMI alone to assess my health?
No. BMI is a screening signal, not a diagnosis. Use it alongside other measures such as waist size, blood pressure and how you feel, and speak to a healthcare professional for a fuller picture.
Related calculators
- Age Calculator — Exact age in years, months and days, plus a countdown to the next birthday.
- All health & fitness tools
Browse all CalculatorWonder calculators or read the guides behind the numbers.