BMI Calculator
Calculate your body mass index (BMI) from height and weight and see the WHO adult category band for the result.
WHO BMI categories last updated · reference source
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Dated static reference; no live data is fetched. Verify current source values and assumptions before relying on results.
What this tool does
Calculate your body mass index (BMI) from height and weight and see the WHO adult category band for the result. Adult WHO bands only — BMI does not distinguish muscle from fat and is not used for children (see the child BMI percentile tool), pregnancy or clinical assessment.
How to use the BMI Calculator
- Enter or select body weight in lb.
- Enter or select height in in.
- Read the calculated result; change any measurement to compare alternatives.
Formula
BMI = weight kg / (height m)²; category from the WHO adult BMI bands
- weight
- Body weight (lb, before metric conversion)
- height
- Height (in, before metric conversion)
Adult WHO bands only — BMI does not distinguish muscle from fat and is not used for children (see the child BMI percentile tool), pregnancy or clinical assessment.
Worked example
For bmi calculator, the following measurements illustrate the exact method: Body weight: 154; Height: 69.
Inputs
- Body weight154 lb
- Height69 in
Result
- BMI22.74
- WHO categoryNormal weight
WHO adult BMI categories
| BMI range | Category |
|---|---|
| Below 16.0 | Underweight (severe thinness) |
| 16.0 – 16.9 | Underweight (moderate thinness) |
| 17.0 – 18.4 | Underweight (mild thinness) |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight (pre-obesity) |
| 30.0 – 34.9 | Obesity class I |
| 35.0 – 39.9 | Obesity class II |
| 40.0 and above | Obesity class III |
Results explained
- BMI
- BMI from the formula above. Adult WHO bands only — BMI does not distinguish muscle from fat and is not used for children (see the child BMI percentile tool), pregnancy or clinical assessment.
- WHO category
- WHO category from the formula above. Adult WHO bands only — BMI does not distinguish muscle from fat and is not used for children (see the child BMI percentile tool), pregnancy or clinical assessment.
Frequently asked questions
BMI = your weight in kilograms divided by your height in metres squared. Enter pounds and inches here — the tool converts them first.
The WHO normal (healthy weight) band is 18.5–24.9. Below 18.5 is underweight, 25.0–29.9 is overweight (pre-obesity), and 30 or above falls in the obesity classes.
BMI only uses height and weight, so dense muscle mass counts the same as fat. Muscular athletes often land in the overweight band despite low body fat — pair BMI with a waist or body-fat measure.
No. For ages 2–20, BMI must be compared with children of the same age and sex as a percentile — use the BMI Calculator for Kids on this site, which uses the CDC LMS growth-chart method.
No. This is a category lookup against published WHO bands, not a diagnosis. Discuss results that concern you with a qualified health professional.