Health
BMI Calculator
Find your Body Mass Index in seconds. Metric or imperial. No signup, no ads above the result, no nonsense.
BMI Calculator
BMI categories (adults, WHO)
| BMI range | Category |
|---|---|
| below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity (class I) |
| 35.0 – 39.9 | Obesity (class II) |
| 40.0 and above | Obesity (class III) |
How to use this BMI calculator
- Choose Metric (cm + kg) or Imperial (ft/in + lb).
- Enter your height and weight.
- Your BMI updates instantly. No button to push.
The BMI formula
BMImetric = weight (kg) ÷ height (m)²
BMIimperial = (weight (lb) × 703) ÷ height (in)²
BMI was developed by Belgian mathematician Adolphe Quetelet in the 1830s as a population statistic, not a personal diagnostic tool. It's a quick screen, not a verdict.
Examples
Example 1
178 cm, 75 kg
BMI = 75 ÷ 1.78² ≈ 23.7 — Healthy weight
Example 2
5'10", 200 lb
BMI = 200 × 703 ÷ 70² ≈ 28.7 — Overweight
Example 3
160 cm, 50 kg
BMI = 50 ÷ 1.6² ≈ 19.5 — Healthy weight
Frequently asked questions
What is a healthy BMI? +
A BMI between 18.5 and 24.9 is generally considered healthy for adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese.
Is BMI accurate? +
BMI is a useful population screening tool but it does not measure body fat directly. Muscular people may have a high BMI without being overfat. Older adults may have low muscle mass and a "normal" BMI while still being at health risk. Use it as a starting point, not a diagnosis.
How is BMI calculated? +
BMI = weight (kg) ÷ height (m)². For imperial: BMI = (weight in lbs × 703) ÷ (height in inches)².
Is BMI different for men and women? +
The formula is identical for men and women, and the healthy range (18.5–24.9) is the same. BMI is interpreted differently for children and teens — they use age- and sex-specific percentile charts instead.
What should I do if my BMI is high? +
A high BMI is a signal to look closer — talk to a doctor, look at waist circumference, body composition, blood pressure, and lifestyle factors. BMI alone is not a diagnosis.