BMI Calculator
Calculate your Body Mass Index in metric or imperial units. Enter weight and height to get your BMI and weight category instantly in your browser.
This calculator is for informational purposes only and does not constitute medical advice. Consult a healthcare professional for guidance on your weight and health.
How BMI is calculated
Body Mass Index is a simple ratio of weight to height squared. In metric units the formula is weight (kg) divided by height (m) squared; in imperial units it is 703 multiplied by weight (lb) divided by height (in) squared. The result falls into four WHO categories: Underweight (below 18.5), Normal (18.5 to 24.9), Overweight (25 to 29.9), and Obese (30 and above). Calculations run entirely in your browser and nothing is sent to a server.
BMI is a population-level screening tool and has known limitations. It does not distinguish between muscle mass and fat mass, and normal ranges may vary by age, sex, and ethnicity. Use it as a rough starting point, not a clinical diagnosis.
FAQ
Which unit system should I use? Either gives the same result. Metric uses kilograms and centimetres; Imperial uses pounds and inches. Switch the toggle at the top to change.
Is my data stored? No. All calculation happens client-side in JavaScript. Nothing is uploaded or logged.
Why does my BMI differ from my doctor's? BMI is calculated the same way everywhere, but your doctor may use adjusted reference ranges or additional measurements such as waist circumference to give a fuller picture.