BMI Calculator (Adults)
Work out body mass index (BMI) from weight and height for adults aged 20 and over, with the standard adult weight categories and the healthy weight range for your height.
For adults 20 and over. Not for children and teens, pregnant women or very muscular people, and it is not a diagnosis. Talk to a doctor about your health.
- BMI
- –
- Weight category
- –
- Healthy weight for your height, from
- –
- Healthy weight for your height, to
- –
How it is calculated
- BMI = weight in kg ÷ (height in metres)²
- Adult categories: under 18.5 underweight; 18.5 to under 25 healthy weight; 25 to under 30 overweight; 30 and over obesity (class 1: 30 to under 35; class 2: 35 to under 40; class 3: 40 and over)
- 1 lb = 0.45359237 kg; 1 inch = 2.54 cm; 1 foot = 30.48 cm
Worked example
70 kg and 175 cm.
| You enter | |
|---|---|
| Weight | 70 |
| Weight unit | Kilograms |
| Height | 175 |
| Height unit | Centimetres |
| You get | |
| BMI | 22.9 kg/m² |
| Weight category | Healthy weight |
| Healthy weight for your height, from | 56.7 kg |
| Healthy weight for your height, to | 76.3 kg |
A BMI of 22.9 is in the "Healthy weight" range for adults. For your height, a BMI of 18.5 to 24.9 means a weight of 56.7 to 76.3 kg.
Questions
Is BMI the same for children?
No. For ages 2 to 19, BMI is compared with growth charts for age and sex, so this adult calculator does not apply.
Sources and checks
Last checked: 15 October 2026. This calculator passes 6 automatic tests before every release.
Your numbers never leave your device: the calculation runs in your browser and nothing you type is sent or stored.
BMI is a screening measure, not a diagnosis: it does not tell fat from muscle. Some health bodies use lower cut-offs for people of South Asian and other Asian backgrounds. For advice about your weight, see a doctor. Results are estimates for information only and are not financial, tax or legal advice. Check important figures with a qualified professional before you act on them.