BMI Calculator
Calculate body mass index from height and weight (metric or imperial).
Enter your height and weight — in metric or imperial units — to calculate your body mass index (BMI) and see which standard category it falls into. Results update as you type.
BMI is a quick, widely used screening number. It is a useful general indicator, but it does not account for muscle, build, age, or sex.
📖 Read the guide: Understanding BMI: What It Measures and What It Misses
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Formula
BMI (metric)
weight (kg) ÷ height (m)² = BMI
Example: 70 kg ÷ (1.75 m)² = 22.9.
BMI (imperial)
703 × weight (lb) ÷ height (in)² = BMI
The 703 factor converts pounds and inches to the metric result.
How to use the bmi calculator
- 1Choose metric or imperial units.
- 2Enter your height and weight.
- 3Read your BMI and category; copy the value if you like.
Examples
| Example | Input | Result |
|---|---|---|
| Metric | 70 kg, 1.75 m | BMI 22.9 (Normal) |
| Imperial | 154 lb, 5'9" | BMI ~22.7 (Normal) |
| Higher | 95 kg, 1.75 m | BMI 31.0 (Obese) |
BMI categories
For adults, the standard World Health Organization categories are: under 18.5 is underweight, 18.5–24.9 is a normal (healthy) weight, 25–29.9 is overweight, and 30 or above is obese. These ranges are the same regardless of sex and apply to adults aged 20 and over.
BMI is calculated the same way worldwide; only the units differ. The imperial formula multiplies by 703 to match the metric result.
What BMI does and doesn't tell you
BMI is a simple ratio of weight to height, which makes it a handy population-level screening tool. But it cannot distinguish muscle from fat, so very muscular people may register as overweight, and it does not reflect where fat is stored or other health factors. Treat it as one general signal, not a diagnosis.
BMI is a general screening tool, not a diagnosis, and does not account for muscle mass, body composition, age, or sex. It is not medical advice — consult a healthcare professional for guidance about your health.
Frequently asked questions
How is BMI calculated?
BMI is weight in kilograms divided by height in metres squared. In imperial units, multiply pounds by 703 and divide by height in inches squared.
What is a healthy BMI?
For adults, a BMI of 18.5–24.9 is considered a normal (healthy) weight. Below 18.5 is underweight; 25–29.9 is overweight; 30 and above is obese.
Is BMI accurate for everyone?
No. BMI doesn't distinguish muscle from fat and doesn't apply the same way to athletes, children, pregnant people, or the elderly. Use it as a general guide.
Is my data private?
Yes. Your height and weight are processed in your browser and never uploaded.
Embed this calculator
Add the BMI Calculator to your own website — free. Copy and paste this snippet:
<iframe src="https://numvella.com/embed/bmi-calculator" width="100%" height="460" style="border:1px solid #e2e8f0;border-radius:12px" title="BMI Calculator — Numvella" loading="lazy"></iframe>