BMI Calculator
Calculate your Body Mass Index using metric or imperial units. Free online BMI Calculator. Calculate bmi online — fast, accurate, mobile-friendly, no signup nee
< 18.5
18.5–24.9
25–29.9
≥ 30
Derivation
- ├── 01Given
height (cm) = 170, weight (kg) = 65 - ├── 02Formula
BMI = weight (kg) / height (m)² - ├── 03Convert height
170 cm = 1.70 m - ├── 04Substitute
65 / (1.70)² - ├── 05Simplify
65 / 2.8900 - ├── 06BMI22.49
- └── 07Classify
BMI 22.5 → Normal
BMI was invented in 1832 by Belgian statistician Adolphe Quetelet — for population studies, not individual health.
Understanding the BMI Calculator
Body Mass Index (BMI) is a simple screening number that relates your weight to your height. It’s used worldwide to categorize a person as underweight, healthy, overweight or obese — but it doesn’t measure body fat directly.
Health metrics give us objective checkpoints against a body that can feel unreliable. Used alongside professional guidance — not in place of it — these numbers help you track progress and spot trends that matter. The BMI Calculator sits in that toolkit — it calculate your Body Mass Index using metric or imperial units. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.
How it’s calculated
Where
- BMI
- Body Mass Index (kg/m²)
- weight
- Body weight in kilograms
- height
- Height in meters (1 m = 100 cm)
Step-by-step walkthrough
A person is 70 kg and 1.75 m tall.
- 01Square the height: 1.75² = 3.0625
- 02Divide weight by height²: 70 / 3.0625 ≈ 22.86
- 03BMI = 22.9 — falls in the "Healthy" range (18.5–24.9)
Frequently asked questions
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