BMI Calculator with WHO and National Standards
Calculate your body mass index in metric or imperial units and see your weight class under the WHO standard or the national standard of Korea, Japan, China, the UK, Indonesia or Thailand, with the healthy weight range for your height.
Any standard can be used on any language page: for example, check a result against the Korean or Japanese classes from abroad.
Classes of this standard (adults)
| BMI | Class | Term in the standard |
|---|
How BMI is calculated and read
- BMI = weight (kg) ÷ height (m)². Imperial units are converted exactly: 1 in = 2.54 cm, 1 lb = 0.45359237 kg, 1 st = 14 lb.
- The class is read from the BMI rounded to one decimal, the way the standards write their limits, so the class always matches the number shown.
- These classes are for adults. Children and teenagers are assessed with growth charts by age and sex, and BMI does not apply in pregnancy.
- BMI does not tell fat from muscle or show where fat is stored. Very muscular people and older adults can be misclassified; waist size adds information.
- Everything runs in your browser. Your height and weight are not sent to LeedyBox or saved.
Source: CDC: Adult BMI Categories; WHO: Body mass index (BMI) · Last checked:
Source: NIST SP 811, Appendix B.8 · Last checked:
Source: Weights and Measures Act 1985, Schedule 1, Part VI · Last checked:
Wrong result? If a class or limit looks wrong for a standard, email us the standard, the BMI shown and what you expected, so we can check it against the source.
Does a sentence on this page sound unnatural in your language? Let us know that too.
How to use
- Choose your units: centimetres and kilograms, feet, inches and pounds, or stones and pounds.
- Enter your height and weight. The BMI and its class appear at once.
- Pick the classification standard. The page starts with the usual standard for your language, but every standard is available on every page.
- Read the normal weight range for your height, and compare your BMI with the table of classes for the standard you chose.
Frequently asked questions
How is BMI calculated?
Divide your weight in kilograms by your height in metres squared. 65 kg at 1.70 m gives 65 ÷ 1.70² = 22.5. In pounds and inches, multiply weight ÷ height² by 703.
What is a healthy BMI?
Under the WHO and US CDC classes, 18.5 to 24.9 is normal weight, 25 to 29.9 overweight and 30 or more obesity. Several Asian standards use lower limits: obesity starts at 25 in Korea and Japan and at 28 in China.
Why are the Asian BMI limits lower?
The UK guideline NICE NG246 explains that people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background are prone to central fat and their cardiometabolic risk starts at a lower BMI. Korea, China and Thailand likewise start overweight or obesity at a lower BMI than the WHO classes.
Can I use the Korean or Japanese standard if I do not live there?
Yes. Pick it under "Classification standard": every standard works on every language page. Use the one your doctor or health check uses.
Does BMI work for children, athletes or pregnant women?
Not with these classes. Children and teenagers need growth charts by age and sex; very muscular people can have a high BMI without excess fat; and BMI is not used to assess weight in pregnancy.
Is my height and weight sent anywhere?
No. The calculation runs in your browser, and the page does not save what you enter.