BMI Calculator
Check your body mass index and healthy weight range. Free
Your measurements
Enter your height and weight.
Adult BMI categories
WHOGood to know
Not medical advice. BMI is a screening tool, not a diagnosis. It does not measure body fat and is not meant for pregnancy, children and teens, or very muscular people such as athletes. Talk to a doctor about your health.
Some health bodies use lower cut-offs for adults of Asian descent, such as 23 for overweight and 27.5 for obesity, because health risks can start at a lower BMI.
About the BMI Calculator
Whisser BMI Calculator works out your body mass index from your height and weight, in metric or imperial units, and shows where it falls on the adult BMI scale. It also gives the healthy weight range for your height, how far you are from it, and two related measures: BMI Prime and the Ponderal index. BMI is a quick screening number, not a diagnosis, so use it as a starting point for a conversation with a health professional.
How to use
- Choose Metric (cm and kg) or Imperial (feet, inches and pounds).
- Type your height and weight, or drag the sliders. The result updates instantly.
- Optionally add your age and sex to see notes that may apply to you.
- Read your BMI, category and healthy weight range, and check the notes below the result.
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared. For example, 65 kg at 1.70 m is 65 ÷ (1.70 × 1.70) = 22.5. In imperial units the calculator converts feet, inches and pounds first, so the result is the same.
What is a healthy BMI for adults?
For most adults, a BMI from 18.5 to 24.9 is classed as a healthy or normal weight. Under 18.5 is underweight, 25 to 29.9 is overweight and 30 or more is obesity, which is split into classes I, II and III. Some health bodies use lower cut-offs for people of Asian descent.
Is BMI accurate for everyone?
No. BMI is a quick screening tool, not a diagnosis. It does not measure body fat directly, so it can overestimate fat in muscular people and athletes and underestimate it in older adults. It is not designed for pregnancy, and children and teens under 20 should use age- and sex-specific BMI-for-age charts instead. Talk to a doctor about your health.
What are BMI Prime and the Ponderal index?
BMI Prime is your BMI divided by 25, the upper limit of the normal range, so a value from 0.74 to 1.0 is in the normal range. The Ponderal index divides weight by height cubed instead of squared, which can suit very tall or very short people better; about 11 to 15 kg/m³ is typical for adults.
Why do you ask for age and sex?
They are optional and do not change the BMI number. They are only used to show notes that may apply to you, such as the use of growth charts for people under 20 or how BMI is read for older adults.
Are my measurements saved or uploaded?
Nothing is uploaded. Your BMI is calculated in your browser, and your last inputs are kept in this browser's local storage so they are there next time. Use Clear to remove them.