BMI Calculator
Enter your height and weight in metric or imperial units to get your body mass index (BMI), its WHO adult category, the healthy weight range for your height and the formula, worked with your numbers. It is a screening number for adults, not a diagnosis.
For adults (20 and over). Not medical advice: BMI is a screening number, not a measure of body fat or health.
BMI categories for adults
The World Health Organization uses the same ranges for adult men and women. The right-hand column shows the extra public-health action points a WHO expert consultation suggested in 2004 for Asian populations, who tend to carry higher health risks at a lower BMI. Pick either set in the calculator above.
| BMI | WHO category | Asian cut-off points |
|---|---|---|
| Below 16 | Underweight (severe thinness) | Underweight (below 18.5) |
| 16 - 16.9 | Underweight (moderate thinness) | |
| 17 - 18.4 | Underweight (mild thinness) | |
| 18.5 - 22.9 | Healthy weight (18.5 - 24.9) | Acceptable risk |
| 23 - 24.9 | Increased risk (23 - 27.4) | |
| 25 - 27.4 | Overweight (25 - 29.9) | |
| 27.5 - 29.9 | High risk (27.5 and above) | |
| 30 - 34.9 | Obesity class I | |
| 35 - 39.9 | Obesity class II | |
| 40 and above | Obesity class III |
The category is read from your BMI rounded to one decimal place, so it always matches the number on screen.
Worked example, in both unit systems
An adult who is 175 cm tall and weighs 70 kg:
The same idea in imperial units for someone 5 ft 9 in tall weighing 160 lb. 5 ft 9 in is 69 inches:
Both are in the WHO healthy range. On the Asian cut-off points the second result, 23.6, is in the increased-risk band, which starts at 23. The calculator converts feet, inches and pounds to metres and kilograms with the exact legal factors (1 in = 2.54 cm, 1 lb = 0.45359237 kg), so its answer can differ from the 703 shortcut in the second decimal place.
What your BMI does and does not tell you
Body mass index compares your weight with your height. Across large groups of adults, a higher BMI goes with a higher risk of type 2 diabetes, high blood pressure and heart disease, which is why doctors use it as a quick first check.
For one person it is a rough guide. It cannot tell muscle from fat, so a muscular athlete can score as overweight, and it does not show where fat is carried. Fat around the waist carries more risk than fat elsewhere. The UK's NICE guidance suggests also checking your waist-to-height ratio and keeping your waist below half your height.
BMI is not used for children and teenagers - they are measured against BMI-for-age growth charts - or during pregnancy. If your result worries you, or you plan to lose or gain a lot of weight, speak to a doctor first.
Frequently asked questions
How is BMI calculated?
What is a healthy BMI?
Is BMI different for South Asian people?
Can I use this BMI calculator for children?
Why can BMI be misleading?
What is BMI Prime?
What this calculator does not do
- It does not give medical advice or diagnose anything. Talk to a doctor or a registered dietitian about your weight and health.
- It uses the adult categories only. It is not for children, teenagers or pregnant women.
- It cannot measure body fat, muscle or waist size; two people with the same BMI can be in very different health.
- Nothing you enter is saved or sent anywhere - the calculation runs in your browser.