About this tool
The BMI Calculator estimates your Body Mass Index from your height and weight, a simple screening measurement used by health professionals to flag underweight, normal, overweight, and obese ranges according to World Health Organization categories. Switch between metric (kilograms and centimeters) and imperial (pounds, feet, and inches) units depending on what you have handy. Along with your BMI number and category, the tool shows a suggested healthy weight range for your height so you can see how far you are from it in either direction. BMI is a quick, widely used starting point, not a diagnosis — it does not account for muscle mass, bone density, or body composition, so athletes and very muscular people may see a higher number than their actual body fat would suggest. Calculations happen instantly in your browser as you type.
How to use
- 1
Choose a Unit System
Select Metric (kg, cm) or Imperial (pounds, feet & inches).
- 2
Enter Height and Weight
Type in your current height and body weight.
- 3
Review Your Result
See your BMI number, category, and healthy weight range appear instantly.
Features
- Metric (kg / cm) and Imperial (lb / ft & in) unit modes
- WHO-standard BMI category classification with a color-coded result
- Suggested healthy weight range calculated for your exact height
- Instant recalculation as you adjust height or weight
- Clear breakdown of the formula used for your result
- No account or signup needed — free to use
Tips & common mistakes
- •If you switch unit systems after entering numbers, re-check the fields — values don't auto-convert between kg/cm and lb/ft-in.
- •BMI alone doesn't separate muscle from fat, so very athletic users may fall in the "overweight" band without carrying excess body fat.
- •For children and teenagers, BMI is interpreted differently (age- and sex-specific percentiles) — this calculator is intended for adults.
- •Use the healthy weight range as a general guide, not a strict target; talk to a healthcare professional for personalized advice.
BMI Formula
Body Mass Index is defined as body mass divided by the square of body height.
Metric: BMI = kg / m² | Imperial: BMI = (lb / in²) × 703- •Metric example: 70 kg at 1.75 m → 70 / (1.75 × 1.75) ≈ 22.9 (normal)
- •Imperial example: 160 lb at 68 in → 703 × 160 / (68 × 68) ≈ 24.3 (normal)