BMI Calculator
| Category | – |
| Healthy weight for your height | – |
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What is BMI?
BMI (Body Mass Index) is a simple screening number that relates your weight to your height. It doesn't measure body fat directly, but for most adults it tracks closely enough to flag weight categories used by doctors worldwide. Enter your height and weight above — in metric or imperial — to see your BMI instantly.
How BMI is calculated
BMI = weight (kg) ÷ height (m)2
In imperial units: BMI = (weight (lbs) ÷ height (in)2) × 703
Categories (WHO):
- Below 18.5 — Underweight
- 18.5 – 24.9 — Normal weight
- 25 – 29.9 — Overweight
- 30 and above — Obese
Worked example
You weigh 70 kg and are 175 cm tall. Height in metres = 1.75, squared = 3.0625. BMI = 70 ÷ 3.0625 = 22.9 — comfortably in the Normal weight range. Your healthy weight range at this height is 56.7 – 76.3 kg. Try it above.
Frequently asked questions
Is BMI accurate?
BMI is a screening tool, not a diagnosis. It can misclassify very muscular people (muscle weighs more than fat) and doesn't account for age, sex, or fat distribution. Doctors use it as a starting point alongside waist measurement and other checks.
What is a healthy BMI?
Between 18.5 and 24.9. The calculator also shows your personal healthy weight range in kg or lbs for your exact height — a more practical target than the index alone.
Does BMI work for children or athletes?
Not directly. Children's BMI is interpreted against age-and-sex percentile charts, and athletes with high muscle mass often score "overweight" while being very fit. This calculator is designed for typical adults.
How can I move into the normal range?
Small sustained changes beat crash diets: a modest daily calorie deficit, regular walking or exercise, more protein and vegetables, and less sugary drinks. Use our Calorie Calculator to find your daily target.