BMI calculator (body mass index)
Body mass index and healthy weight range
- Healthy weight for your height
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- To reach a healthy weight
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For adults aged 18 and over. BMI gives a misleading picture for children, pregnant women and very muscular people. Treat it as a guide, not a substitute for seeing a doctor.
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BMI (body mass index) is your weight in kilograms divided by your height in metres squared. At 175 cm and 80 kg that gives 80 / 1.75² = 26.1, which counts as overweight. A healthy BMI for adults runs from 18.5 to 24.9. Enter your height and weight to see the healthy range for you.
How it works
BMI = weight (kg) / height (m)². Turn centimetres into metres first: 175 cm is 1.75 m, and 1.75² is 3.0625.
- below 18.5: underweight
- 18.5 to 24.9: healthy weight
- 25 to 29.9: overweight
- 30 to 34.9: obesity class I
- 35 to 39.9: obesity class II
- 40 or more: obesity class III
The World Health Organization uses the same bands for men and women. BMI can't tell muscle from fat, so a 100 kg rugby player may score over 30 with very little fat. That's why doctors also measure the waist. Risk goes up above 80 cm for women and 94 cm for men.
Worked example
Tom is 182 cm tall and weighs 95 kg. His BMI is 95 / 1.82² = 28.7, in the overweight band. A healthy weight at his height is 61.3 to 82.5 kg, so he is 12.5 kg above the top of that range.
Ana is 164 cm and 52 kg. Her BMI of 19.3 is healthy, though towards the lower end.
If you think in feet and stone, convert first: 5 ft 11 in is about 180 cm, and 14 stone is about 89 kg.
Questions people ask
What is a good BMI for my age?
For adults the bands don't change with age: anything from 18.5 to 24.9 is healthy. There's no single ideal number, and the difference between 20 and 24 matters little for health.
Is BMI calculated the same way for children?
The sum is the same, but the result is read differently. For children and teenagers it's compared with growth charts for their age and sex, as a percentile. A GP or paediatrician does that.
How much should I weigh for my height?
Square your height in metres, then multiply by 18.5 and by 24.9. For 170 cm that's roughly 53.5 to 72 kg.
What is ITM on a Serbian medical report?
ITM stands for indeks telesne mase, the Serbian name for BMI. It's the same figure.
Sources
- WHO: A healthy lifestyle, WHO recommendations (BMI) — checked 13 November 2026
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Updated: 13 November 2026