About BMI Calculator
Calculate your Body Mass Index (BMI) from your height and weight, and see which category it falls into. BMI is a quick screening measure of whether your weight is in a healthy range for your height.
How to Use
- Choose metric (kg/cm) or imperial (lb/in) units.
- Enter your height and weight.
- Read your BMI value.
- See which category it falls into (underweight, normal, overweight, obese).
Why Use This Tool?
- Accurate — built on precise, well-tested mathematical formulas.
- Instant — all calculations happen client-side for zero latency.
- Private — no data is sent to any server; your information stays on your device.
- Free — no sign-up, no limits, no hidden costs.
Frequently Asked Questions
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². For example, 70 kg at 1.75 m gives 70 ÷ (1.75 × 1.75) = 22.9. In imperial units it is 703 × weight (lb) ÷ height (in)².
What is a healthy BMI range?
The WHO ranges are: below 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30+ obese. Some health bodies use lower thresholds for South Asian populations.
Is BMI accurate for everyone?
BMI is a useful general screen but does not distinguish muscle from fat. Very muscular people may read as 'overweight', so treat it as one indicator, not a diagnosis.