BMI Calculator
Work out your body mass index (BMI) from your height and weight, see which WHO weight category it falls in, and the weight range for a BMI of 18.5 to 24.9 at your height.
Your details
Your results
Enter your height and weight to see your BMI.
Your BMI
A BMI of 18.5 to 24.9 at your height is .
How to use it
- Choose metric (kg, cm) or imperial (lb, ft/in).
- Enter your height and your current body weight.
- Read your BMI, its category, and the weight range for a BMI of 18.5 to 24.9 at your height.
How it's calculated
BMI is your weight divided by your height squared:
- Metric: BMI = weight (kg) ÷ height (m)²
- Imperial: BMI = 703 × weight (lb) ÷ height (in)²
Example: 75 kg at 1.78 m is 75 ÷ (1.78 × 1.78) = 23.7.
The adult categories come from the World Health Organization:
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Normal weight |
| 25.0 to 29.9 | Overweight |
| 30.0 to 34.9 | Obesity class I |
| 35.0 to 39.9 | Obesity class II |
| 40.0 and above | Obesity class III |
The weight range shown for your height is the range that gives a BMI of 18.5 to 24.9.
BMI is a quick screening number for groups of adults. It doesn’t measure body fat, and it doesn’t account for muscle mass, age, sex or ethnicity. It isn’t meant for children, teenagers or pregnant women.
Sources
- World Health Organization (2000). Obesity: preventing and managing the global epidemic. Report of a WHO consultation. WHO Technical Report Series 894. Geneva: WHO.
Questions
Is BMI accurate for people who lift weights?
Often not. BMI only uses height and weight, so it can't tell muscle from fat. Many strength athletes have a BMI above 25 with low body fat. A waist measurement or a body fat estimate tells you more.
Can I use this for children or teenagers?
No. Under 18, BMI is compared with growth charts for age and sex, not with these adult categories.
Why does my category change at exactly 25.0?
The categories have fixed cut-offs. The calculator uses the BMI rounded to one decimal, the number you see on screen, so the category always matches it.
Updated October 24, 2026.