BMI calculator
Find your BMI and the healthy range for your height.
Normal weight (WHO)
Healthy weight for this height: 59.9 to 80.7 kg
BMI is a screening number based on height and weight, not a diagnosis. It does not measure body fat directly. Children and teens need BMI-for-age percentiles, not these adult categories.
- Metric or imperial units
- WHO adult weight categories
- Healthy weight range for your height
How to calculate BMI
- Pick metric or imperial units.
- Enter height and weight.
- Read the BMI, category and healthy weight range.
The BMI formula
In metric, BMI is weight in kilograms divided by height in meters, squared: BMI = kg / m^2. In imperial, it is BMI = 703 x lb / in^2, a scaling constant that makes the same weight and height categories work with pounds and inches instead.
Both formulas measure the same thing: how heavy someone is relative to the square of their height, not their actual body composition. Squaring the height rather than using it directly is what lets the formula compare people of different heights fairly, since weight alone rises roughly with the square of height in people of similar build.
Worked examples
| Height and weight | BMI | WHO category |
|---|---|---|
| 165 cm, 60 kg | 22.0 | Normal weight |
| 5 ft 9 in, 180 lb | 26.6 | Overweight |
| 175 cm, 90 kg | 29.4 | Overweight, close to the obese cutoff |
The last example shows why the categories are a range, not a single number: 29.4 and 30.0 describe almost the same body, but only one crosses into the next WHO band.
WHO adult BMI categories
| BMI | Category | What it means |
|---|---|---|
| Below 18.5 | Underweight | Lower body weight for height than typical |
| 18.5 to 24.9 | Normal weight | The range associated with the lowest average health risk |
| 25 to 29.9 | Overweight | Above the normal range, before the obese band |
| 30 and above | Obese | Well above the normal range |
What BMI does not measure
- Body fat percentage. BMI only compares weight to height, so it cannot tell muscle from fat.
- Where fat is carried. Two people with the same BMI can carry very different amounts of visceral fat.
- Anything about children or teenagers, who need BMI-for-age percentile charts instead of these fixed adult bands.
- A diagnosis. A doctor or other provider looks at BMI alongside other measurements before drawing any conclusion about a person's health.
BMI calculator FAQ
What is the BMI for 180 cm and 75 kg?
23.1, which falls in the WHO normal weight range of 18.5 to 24.9.
What are the WHO adult BMI categories?
Under 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight, and 30 or above is obese.
Does BMI measure body fat?
No. BMI only compares weight to height. It does not directly measure body fat, muscle mass or where fat is carried, so an athlete with a lot of muscle can score higher than expected.
Is BMI a diagnosis?
No. BMI is a screening number, not a diagnosis. A healthcare provider looks at BMI alongside other factors before drawing any conclusion.
Can I use this for a child or teenager?
No. Children and teens need BMI-for-age percentile charts instead of the fixed adult categories used here, since healthy BMI changes with age and sex during growth.
Is a BMI of 25 a hard cutoff?
No. 25 is where the WHO overweight band starts, but BMI changes gradually and a person at 24.8 is not meaningfully different from one at 25.1. Treat the categories as a rough guide, not a strict line.
Does BMI differ between men and women?
No. The standard adult formula and the WHO categories used here are the same for men and women, even though body fat percentage at a given BMI often differs between the two.
Who invented the BMI formula?
Belgian mathematician Adolphe Quetelet worked out the underlying weight-to-height-squared formula in the 1830s as a population statistic, not a personal health check. It was renamed body mass index and adopted for individual screening more than a century later.