BMI calculator
Stone and pounds or kilos. Uses the NHS bands, with the NICE lower thresholds if they apply to you. For adults 18 and over.
Your details
Not for use in pregnancy. Under 18? Use the NHS BMI calculator for children.
Your BMI
24.1
In the healthy range
That is in the healthy range for your height. Nice. BMI is one number, not the whole picture, but it is a good one to have.
A healthy weight for 5 ft 7 in is about 8 st 6 lb to 11 st 5 lb.
Your result
What the numbers mean
These are the adult bands from NICE guideline NG246, which the NHS uses.
Most adults
| BMI | What it is called |
|---|---|
| Under 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight |
| 25 to 29.9 | Overweight |
| 30 to 34.9 | Obesity class 1 |
| 35 to 39.9 | Obesity class 2 |
| 40 or more | Obesity class 3 |
Lower thresholds
| BMI | What it is called |
|---|---|
| Under 18.5 | Underweight |
| 18.5 to 22.9 | Healthy weight |
| 23 to 27.4 | Overweight |
| 27.5 to 32.4 | Obesity class 1 |
| 32.5 to 37.4 | Obesity class 2 |
| 37.5 or more | Obesity class 3 |
For people with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background (NICE NG246 1.9.11).
At a glance
A healthy weight for your height
The weight range that gives a BMI of 18.5 to 24.9 for common heights.
| Height | Healthy weight range | In kilos |
|---|---|---|
| 5 ft 0 in | 6 st 11 lb to 9 st 1 lb | 43 to 58 kg |
| 5 ft 2 in | 7 st 3 lb to 9 st 10 lb | 46 to 62 kg |
| 5 ft 4 in | 7 st 10 lb to 10 st 5 lb | 49 to 66 kg |
| 5 ft 6 in | 8 st 3 lb to 11 st 0 lb | 52 to 70 kg |
| 5 ft 8 in | 8 st 10 lb to 11 st 10 lb | 55 to 74 kg |
| 5 ft 10 in | 9 st 3 lb to 12 st 6 lb | 58 to 79 kg |
| 6 ft 0 in | 9 st 10 lb to 13 st 2 lb | 62 to 83 kg |
| 6 ft 2 in | 10 st 4 lb to 13 st 12 lb | 65 to 88 kg |
The working
How BMI is worked out
BMI is your weight in kilograms divided by your height in metres, squared.
BMI = kg ÷ (m × m)
For someone who is 11 st 0 lb and 5 ft 7 in, that is 69.9 kg and 1.702 m. 1.702 × 1.702 = 2.897, and 69.9 ÷ 2.897 = 24.1.
The sum dates back to Adolphe Quetelet in 1832. It was named body mass index in 1972.
A better picture
Add your waist
NICE suggests checking your waist to height ratio alongside BMI. Measure round your middle, halfway between your lowest rib and the top of your hip bone.
Read with care
What BMI cannot tell you
BMI is a quick screening measure. It is useful, but it does not know you.
- MuscleBMI cannot tell muscle from fat. Waist to height is a better check if you are very active.
- Family backgroundSome groups have higher health risks at a lower BMI, which is why NICE lower thresholds exist.
- Under 18Children and teenagers need the NHS child BMI calculator instead.
- PregnancyBMI is not used in pregnancy. Your midwife will guide you.
- 65 or overA slightly higher BMI can be protective as you get older. Talk to your GP rather than chasing a number.
- How you feelEnergy, sleep, mood and what you can do day to day matter too.
Questions
Common questions
What is a healthy BMI for adults in the UK?
For most adults, a BMI of 18.5 to 24.9 is in the healthy weight range. If your family background is South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean, NICE suggests a healthy range of 18.5 to 22.9.
Why does my family background change the result?
People from these backgrounds tend to have a higher risk of type 2 diabetes and heart disease at a lower BMI. So NICE uses lower thresholds: overweight from 23 and obesity from 27.5. It is about health risk, not about how anyone looks.
Does BMI work if I am very muscly?
Not very well. Muscle is heavier than fat, so rugby players and people who lift can get a high BMI while carrying little fat. Your waist to height ratio is a better check.
Can I use this for my child, or in pregnancy?
No. Children and teenagers are compared with others of the same age and sex, so use the NHS BMI calculator for children. BMI is not used in pregnancy, and your midwife will talk you through what is right for you.
Is BMI different for older adults?
A slightly higher BMI can be protective as you get older, especially over 65. Rather than aiming for a number, talk to your GP about what is right for you.
Sources
- NHS: BMI calculator for adults
- NICE NG246: identifying and assessing overweight and obesity (bands 1.9.10, lower thresholds 1.9.11, waist to height 1.9.8)
- NHS: BMI calculator for children and teenagers
Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.
When to talk to someone
Talk to your GP if your weight has changed a lot without trying, you are worried about your weight, or you have other symptoms. If food or your body feels hard to think about, Beat has a free helpline on 0808 801 0677. In an emergency, call 999.
Related
Related calculators
- Waist to height ratio calculatorNICE says keep your waist under half your height. Check yours.Open
- Healthy weight calculatorThe healthy weight range for your height, in stone or kilos.Open
- Body fat calculatorBody fat from a tape measure, with the healthy range for your age.Open
- Calorie calculatorEstimate daily calories for weight loss, maintenance or gain.Open
- TDEE calculatorYour everyday energy number, every activity level shown.Open
- Waist to hip ratio calculatorWaist divided by hips, against the WHO cut-offs.Open