BMI Calculator
Calculate your Body Mass Index and see your health category.
BMI Categories:
Underweight: < 18.5
Normal weight: 18.5 – 24.9
Overweight: 25 – 29.9
Obese: 30+
Normal weight: 18.5 – 24.9
Overweight: 25 – 29.9
Obese: 30+
How to Calculate Your BMI
- Enter your weight — type your weight in kilograms (e.g. 70).
- Enter your height — type your height in centimetres (e.g. 175 for 1m 75cm).
- Click "Calculate BMI" — your BMI score appears with a colour-coded health category.
- Read your result — see whether you're underweight, normal weight, overweight, or obese according to WHO guidelines.
Frequently Asked Questions
What is BMI? ▼
BMI (Body Mass Index) is a measure of body fat based on height and weight. It's calculated as weight (kg) divided by height (m) squared. It's widely used as a screening tool to identify healthy and unhealthy weight ranges in adults.
What is a healthy BMI range? ▼
For adults aged 18+, the World Health Organization (WHO) defines: Underweight as below 18.5, Normal weight as 18.5–24.9, Overweight as 25–29.9, and Obese as 30 or above.
How is BMI calculated? ▼
BMI = weight (kg) ÷ height (m)². For example: 70 kg ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9. In imperial units, BMI = (weight in lbs × 703) ÷ height in inches².
Is BMI accurate for everyone? ▼
BMI is a useful general screening tool but not a direct measure of body fat. Athletes may have a high BMI due to muscle mass. The elderly may have a normal BMI but high body fat percentage. For a complete health assessment, consult a healthcare professional.
Does BMI apply to children? ▼
For children and teenagers (2–19 years), BMI is interpreted using age- and gender-specific percentile charts rather than fixed thresholds. This calculator uses the standard adult BMI thresholds and is designed for adults aged 18 and over.