BMI Calculator
Calculate your Body Mass Index and healthy weight range.
How this works
BMI (Body Mass Index) is a simple measure of body fat based on height and weight. It is used by healthcare professionals as a quick screening tool, though it does not directly measure body fat percentage or muscle mass.
The formula
In imperial: BMI = (weight (lbs) ÷ height (in)²) × 703
Example calculation
- Convert height: 5′10″ = 70 inches = 1.778 metres
- Weight: 180 lbs = 81.6 kg
- Apply formula: 81.6 ÷ (1.778 × 1.778) = 81.6 ÷ 3.16 = 25.8
- Result: BMI 25.8 → Overweight (25–29.9 range)
Frequently asked questions
schema.org/FAQPage ✓Is BMI an accurate measure of health?+
BMI is a useful population-level screening tool, but it has limitations. It does not distinguish between fat and muscle mass, so very muscular individuals may be classified as overweight. It also does not account for body fat distribution, age, or sex differences in fat distribution.
What is a healthy BMI range?+
The WHO defines healthy BMI as 18.5–24.9 for adults. Below 18.5 is underweight; 25–29.9 is overweight; 30 and above is obese. However, these thresholds were derived primarily from studies on European populations, and some health organisations recommend lower thresholds for Asian populations.
How is BMI calculated for children?+
For children and teens aged 2–19, BMI is calculated the same way but then compared to age and sex-specific percentile charts rather than fixed thresholds, because children's body composition changes as they grow.