BMI Calculator
Calculate Body Mass Index from metric or imperial inputs and see exactly where the value lands in the official WHO weight categories.
| BMI | WHO category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obesity |
BMI is a screening measure, not a diagnosis — it does not account for muscle mass, age or body composition.
This tool runs entirely in your browser. Your data never leaves your device — it is not uploaded to any server.
How to use
- 1Choose metric (cm + kg) or imperial (ft + in + lb) units.
- 2Type your height and weight.
- 3Read your BMI, its WHO category and the full reference table.
BMI Calculator
Enter height and weight in centimeters and kilograms, or feet, inches and pounds, and the calculator shows your Body Mass Index to one decimal together with the WHO category it falls into — underweight, normal, overweight or obesity — with the matching row highlighted in the reference table.
The result updates as you type, so it is easy to see how a few kilograms move you between bands. BMI is a screening measure, not a diagnosis: it does not distinguish muscle from fat.
Frequently asked questions
What are the WHO BMI ranges?
The World Health Organization defines: below 18.5 underweight, 18.5–24.9 normal weight, 25.0–29.9 overweight, and 30.0 and above obesity. The same cut-offs apply to adult men and women.
How is BMI calculated?
BMI is weight in kilograms divided by height in meters squared (kg/m²). For imperial units the tool converts feet, inches and pounds internally, so the result is identical either way.
Why does BMI not fit athletes?
Muscle is denser than fat, so very muscular people can score “overweight” while carrying little excess fat. Treat BMI as a quick population-level screen and combine it with waist measurement or body composition for a fuller picture.
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