BMI Calculator
Work out your body mass index in kilograms and centimetres or pounds and feet, see your category, and find the healthy weight range for your height.
Key facts
- BMI = weight (kg) ÷ height (m)². In US units: 703 × weight (lb) ÷ height (in)².
- For adults, a BMI of 18.5 to 24.9 is the healthy range, 25 to 29.9 overweight and 30 or more obesity (WHO).
- For many Asian adults, health risks start lower, at around 23.
BMI categories for adults
| BMI | Category (WHO) | Asian adults (WHO, 2004) |
|---|---|---|
| Below 18.5 | Underweight | Underweight |
| 18.5 to 22.9 | Healthy range | Healthy range |
| 23 to 24.9 | Healthy range | Increased risk |
| 25 to 27.4 | Overweight | Increased risk |
| 27.5 to 29.9 | Overweight | High risk |
| 30 to 34.9 | Obesity class I | High risk |
| 35 to 39.9 | Obesity class II | High risk |
| 40 or more | Obesity class III | High risk |
Example
80 kg ÷ (1.75 m × 1.75 m) = 80 ÷ 3.0625 = 26.1
A person who is 175 cm (5′9″) and 80 kg (176 lb) has a BMI of 26.1, which is in the overweight range. The healthy range for that height is about 57 to 76 kg (125 to 168 lb).
What BMI can and can’t tell you
BMI is a quick, free screening number that works well for groups of people. For one person it misses a lot:
- Muscle vs fat. Muscular people can read as “overweight” with little body fat. Check your body fat percentage too.
- Where fat sits. Fat around the waist carries more risk. A simple extra check: keep your waist under half your height (waist-to-height ratio below 0.5).
- Age, sex and ethnicity. The same BMI can mean different body fat for different people.
- Children and teens need BMI-for-age percentiles, not these adult categories.
If your BMI is outside the healthy range, use the TDEE calculator to set a realistic calorie target, and talk to a doctor if you have health concerns.
Track your weight trend in the app
Calculators give an estimate. Log your weight and food for two weeks and the TDEE Calculator app works out what your body really burns, then keeps your target up to date.
- Measured TDEE from your own weight trend and food log
- Food diary with 356 everyday foods from around the world and a barcode scanner
- AI coach and photo calories: snap your plate, check the estimate, add it
- 74 languages, metric or US units, Ramadan mode and reminders
- Private: your log stays on your phone. No ads, no trackers
BMI calculator questions
What is a healthy BMI?
For adults, 18.5 to 24.9. For many people of South Asian, Chinese and other Asian backgrounds, risks for type 2 diabetes and heart disease rise from about 23, so aiming for the lower half of the range makes sense.
How do I calculate BMI in pounds and inches?
Multiply your weight in pounds by 703, then divide by your height in inches squared. For 176 lb and 69 in: 703 × 176 ÷ (69 × 69) = 26.0.
Is BMI accurate for athletes?
Not very. BMI can’t tell muscle from fat, so strong, muscular people often read as overweight. Body fat percentage or waist size are better checks.
Does BMI change with age?
The adult categories are the same at every age from 18, though body fat at the same BMI tends to rise with age. Children and teens use separate charts.
How much should I weigh for my height?
The calculator shows the weight range for a BMI of 18.5 to 24.9 at your height. The ideal weight calculator adds four classic formulas.
Sources
- World Health Organization. Obesity and overweight (fact sheet). www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
- WHO Expert Consultation. Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. Lancet. 2004;363(9403):157-163. doi.org/10.1016/S0140-6736(03)15268-3
- National Institute for Health and Care Excellence (NICE). Overweight and obesity management (NG246), 2025: waist-to-height ratio.