⚖️ BMI Calculator
Enter your weight and height to calculate your Body Mass Index (BMI), along with the WHO weight category it falls into.
Body Mass Index, WHO categories.
How the BMI Calculator works
BMI is calculated as weight in kilograms divided by height in meters squared. The WHO categories are: under 18.5 (underweight), 18.5–24.9 (normal), 25–29.9 (overweight), and 30+ (obese).
Step-by-step calculation
- 1Enter height and weight (metric or US).
- 2Convert height to meters (or keep inches).
- 3Square the height.
- 4Divide weight by squared height (× 703 for US units) and compare with the WHO categories.
Worked example
70 kg at 1.75 m: 70 ÷ 3.0625 = 22.9 (normal). 154 lb at 5 ft 9 in: 703 × 154 ÷ 69² = 22.7.
BMI Calculator examples
| Weight (kg) | BMI |
|---|---|
| 50 | 16.3 — Underweight |
| 60 | 19.6 — Normal weight |
| 70 | 22.9 — Normal weight |
| 85 | 27.8 — Overweight |
| 100 | 32.7 — Obese |
Height 175 cm. Other inputs kept at the calculator's default values. Results calculated by this calculator.
Why use a BMI Calculator?
Get a quick screening number for weight relative to height.
Important factors that can affect your results
- BMI cannot tell muscle from fat.
- It does not show where fat is stored.
- Children use growth charts, not adult categories.
Frequently asked questions
Is BMI a perfect health measure?
No — BMI doesn't account for muscle mass, bone density, or body composition. It's a general population-level screening tool, not a diagnosis.
Should I make health decisions based on BMI alone?
No — talk to a healthcare provider for a fuller picture of your health.
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Last reviewed November 2026 · How we build and check our tools · Report a problem