Health
BMI calculator
Body Mass Index measures whether your weight is appropriate for your height. Enter metric (kg, cm) or imperial (lb, ft+in) values to see your BMI and the WHO category it falls into.
Formula
BMI was developed in the 1830s by Belgian statistician Adolphe Quetelet as a population-level proxy for body fat. It compares your mass to your height squared, producing a single number that loosely indicates whether you are underweight, normal weight, overweight, or obese.
BMI is fast, free, and reproducible — but it ignores body composition (muscle vs. fat), bone density, age, sex, and ethnicity. A muscular athlete and a sedentary person of the same height and weight will get identical BMIs even though their health profiles differ. Use BMI as a rough screening tool and pair it with waist circumference or body-fat measurement for a fuller picture.
All calculations happen in your browser. Nothing is sent to a server.
Examples
- 01A person weighing 70 kg and 175 cm tall→ 70 ÷ 1.75² = 70 ÷ 3.0625 = 22.9 — Normal
- 02A person weighing 154 lb and 5′9″→ 703 · 154 ÷ 69² = 22.7 — Normal
- 03A person weighing 95 kg and 175 cm tall→ 95 ÷ 3.0625 = 31.0 — Obese
FAQ
- WHO categories: Underweight (< 18.5), Normal (18.5–24.9), Overweight (25.0–29.9), Obese (≥ 30.0). Obesity is further split into Class I (30–34.9), II (35–39.9), and III (≥ 40).