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BMI calculator
Body mass index from your weight and height, with the healthy range.
Quick answer
BMI, or body mass index, relates weight to height and puts the result into a standard category. Formula: BMI = weight in kg ÷ (height in metres)². A person who weighs 70 kg and is 175 cm tall has a BMI of 22.9, in the normal range.
Read the guide: How to calculate BMI and what the result means
Your BMI
22.9
- Category (WHO)
- Normal weight
- Healthy weight for your height
- 56.7 to 76.3 kg
BMI does not see muscle, bone or where fat sits. Some Asian health guidelines use lower cut-offs, with overweight starting near 23. A general estimate, not medical advice. Talk to a doctor or dietitian about your own health.
How is BMI calculated?
BMI is a quick screening number: weight divided by height squared.
It is a rough guide only. A muscular athlete can score as overweight, and an older person can have a normal BMI with little muscle.
Waist size, fitness and blood tests tell a doctor much more than BMI alone.
What is the formula for BMI?
- BMI = weight in kg ÷ (height in metres)²
- WHO categories: under 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, 30 and above obese
Can you show a worked example of BMI?
70 kg at 175 cm (1.75 m): 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9, which is normal weight. The healthy range for that height is 56.7 to 76.3 kg.
What is a healthy weight for my height?
The weights that give a BMI of 18.5 to 24.9, the WHO normal range. A general guide, not medical advice.
| Height | Healthy weight range |
|---|---|
| 150 cm | 41.6 to 56.0 kg |
| 155 cm | 44.4 to 59.8 kg |
| 160 cm | 47.4 to 63.7 kg |
| 165 cm | 50.4 to 67.8 kg |
| 170 cm | 53.5 to 72.0 kg |
| 175 cm | 56.7 to 76.3 kg |
| 180 cm | 59.9 to 80.7 kg |
| 185 cm | 63.3 to 85.2 kg |
| 190 cm | 66.8 to 89.9 kg |
Common questions
What is a healthy BMI?
The WHO range for normal weight is 18.5 to 24.9. Some Asian guidelines set the upper end lower.
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so a very fit person can have a high BMI and a healthy body.
Does BMI work for children?
Children are judged against age and sex charts, not these adult cut-offs. Ask a paediatrician.
How can I lower my BMI?
Changes in eating and activity over time. A doctor or dietitian can give a safe plan for you.