BMI Calculator
Body mass index from your height and weight, with its category.
Enter your height and weight to see your BMI.
How it works
BMI compares weight to height by dividing weight in kilograms by height in metres squared. Imperial entries are converted to metric first. The categories shown are the standard adult WHO bands; they aren't intended for children, pregnancy, or people with a lot of muscle mass, where the same number means something different.
BMI = weight (kg) ÷ height² (m²)Example
70 kg at 1.75 m is 70 ÷ (1.75 × 1.75) ≈ 22.9 — within the healthy range.
BMI is a general screening measure and does not replace medical advice or a diagnosis. Speak to a healthcare professional about your individual circumstances.
About this calculator
Body mass index is weight relative to height — kilograms divided by height in metres squared. This calculator takes height and weight in metric or imperial units (feet and inches included), computes the BMI, and shows which standard adult category it falls in along with the weight range that category considers healthy for your height.
BMI is a population-level screening measure, not a diagnosis: it doesn't distinguish muscle from fat, so athletic builds can read 'overweight' while perfectly fit. Treat it as one data point, not a verdict.
Frequently asked questions
What is the BMI formula?
BMI = weight in kilograms ÷ (height in metres)². In imperial units the equivalent is weight in pounds ÷ (height in inches)² × 703. Both give the same number for the same body.
What are the standard BMI categories?
For adults: under 18.5 is underweight, 18.5–24.9 is the healthy range, 25–29.9 is overweight, and 30 and above is obese. The calculator shows these bands alongside your result.
Is BMI accurate for everyone?
No. It ignores body composition, so muscular people can score high without excess fat, and it isn't designed for children, pregnancy or the elderly, where different reference measures apply. Talk to a healthcare professional before acting on it.