BMI Calculator — Body Mass Index (kg/m²)
A BMI calculator works out your Body Mass Index from your weight and height. BMI is a screening measure used around the world to place adults into weight categories.
How it works
- Enter your weight and height (metric or imperial).
- Your BMI is calculated instantly using the standard formula.
- See which category you fall in and the healthy weight range for your height.
Formula
Worked example
A person who weighs 70 kg and is 1.75 m tall has a BMI of 22.9 (70 ÷ 1.75²), which is in the healthy weight range of 18.5 to 24.9.
Frequently asked questions
How do I calculate BMI?
Divide your weight in kilograms by your height in metres squared. For example, 70 kg ÷ (1.75 × 1.75) = 22.9.
What is a healthy BMI?
For most adults, a BMI of 18.5 to 24.9 is classed as healthy weight. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obesity.
Is BMI accurate?
BMI is a useful screening tool, but it does not measure body fat directly. Very muscular people, athletes and older adults can get misleading results, so treat it as a guide, not a diagnosis.
What is the BMI formula in kg/m²?
BMI = weight in kilograms divided by height in metres squared (kg/m²).
What is a healthy BMI for my age?
The adult categories are the same at any age, but BMI is interpreted differently for children and teenagers, who use age-based percentile charts.
Is there a BMI calculator for men and women?
Yes — this calculator works for both. The formula is the same for adult men and women, though body composition can differ.