BMI Calculator
Calculate Body Mass Index (BMI) from your height and weight, with unit toggles for centimeters or feet/inches, and kilograms or pounds. BMI is computed as weight in kilograms divided by height in meters squared (kg/m²), and the result is classified against the standard World Health Organization thresholds: underweight, normal weight, overweight, and obese. BMI is a quick, widely used population-level screening measure, not a diagnosis — it doesn't distinguish muscle mass from fat mass, so athletes and very muscular people are often classified as 'overweight' despite low body fat. Use it as one data point, not a substitute for a conversation with a healthcare provider.
By The Paper Room Editorial Team — Financial & Utility Tools
Frequently asked questions
What is the BMI formula?▼
BMI = weight (kg) ÷ height (m)². If you're using pounds and inches, the equivalent formula is BMI = 703 × weight (lb) ÷ height (in)². This calculator handles the unit conversion for you when you toggle between metric and imperial.
What are the WHO BMI categories?▼
Under 18.5 is classified as underweight, 18.5 to 24.9 as normal weight, 25 to 29.9 as overweight, and 30 or above as obese. These thresholds are the standard adult classification used by the World Health Organization and most public health bodies; they don't apply the same way to children, where age- and sex-specific percentile charts are used instead.
Is BMI accurate for everyone?▼
No. BMI doesn't measure body fat directly and can't distinguish muscle from fat, so it commonly misclassifies muscular athletes as overweight or obese, and can under-flag people with low muscle mass but high body fat. It's also less reliable across some ethnic groups, in older adults, and during pregnancy. Waist circumference, body fat percentage, and a clinical assessment give a fuller picture.
What's a healthy BMI range?▼
For most adults, 18.5 to 24.9 is considered the normal/healthy range by WHO standards. That said, 'healthy' varies by individual — factors like muscle mass, frame size, age, and overall health matter alongside the number itself.
Does this store or send my height and weight anywhere?▼
No — the calculation happens entirely in your browser using JavaScript. Nothing you enter is transmitted to a server or saved anywhere.