BMI Calculator
Calculate your Body Mass Index in metric or imperial units.
🔒 100% browser-based — your data never leaves your device.
About this tool
Body Mass Index (BMI) is a quick screening number computed from height and weight: weight in kilograms divided by height in meters squared. Enter your measurements in metric (cm/kg) or imperial (ft-in/lb) and the calculator returns your BMI along with the WHO classification: underweight (below 18.5), normal (18.5–24.9), overweight (25–29.9) or obese (30+).
BMI is a population-level screening tool, not a diagnosis — it does not distinguish muscle from fat. Athletes and older adults in particular should treat it as a rough guide and consult a professional for a real assessment.
Frequently asked questions
What is a healthy BMI?
The WHO defines the normal range as 18.5 to 24.9. Some Asian-Pacific guidelines use 18.5 to 22.9 as normal, with overweight starting at 23.
Is BMI accurate for everyone?
No. It overestimates body fat for muscular people and can underestimate it for older adults with low muscle mass. Use it as a screening signal, not a verdict.
How is BMI calculated?
Weight in kilograms divided by height in meters squared. Example: 70 kg ÷ (1.75 m)² = 22.9.