BMI Calculator
Calculate your body mass index (BMI) from height and weight. Supports metric (cm, kg) and imperial (ft/in, lb) units. BMI helps assess whether your weight is healthy for your height. Free, instant results.
BMI calculator
Result
What is this?
BMI (body mass index) is a measure of body fat based on height and weight. It is calculated as weight in kg divided by height in meters squared. BMI categories range from underweight to obese. It does not account for muscle mass or body composition, so it has limitations. Athletes and very muscular people may fall into "overweight" or "obese" categories despite being healthy. For most people, BMI provides a useful screening tool. The calculator supports both metric (cm, kg) and imperial (ft/in, lb) units.
When to use
Use for a quick health screening, tracking weight goals, or understanding where you fall on the BMI scale. Note: BMI is a screening tool, not a diagnostic. Athletes with high muscle mass may have high BMI despite being fit. Doctors and nutritionists use it as a starting point for discussions. Fitness enthusiasts track it over time. Insurance and health programs sometimes use BMI for risk assessment. Always combine with other health indicators for a full picture.
How to use
Enter your height and weight. BMI is calculated as weight (kg) divided by height (m) squared. Use the unit selectors for cm/ft-in and kg/lb.
Formula
BMI = weight (kg) ÷ height (m)²
BMI categories
- Under 18.5: Underweight
- 18.5 – 24.9: Normal
- 25 – 29.9: Overweight
- 30 and above: Obese
Frequently asked questions
- BMI = weight (kg) ÷ height (m)². For example, 70 kg and 1.75 m gives BMI = 70 ÷ (1.75 × 1.75) ≈ 22.9.
- A BMI between 18.5 and 24.9 is generally considered normal. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese.