BMI Calculator
Use the BMI Calculator for a general estimate based on your height and weight. The result can help you start a health conversation, but it does not measure body fat or describe your complete health.
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Last reviewed January 15, 2026 — see our editorial & accuracy policy.
Method: BMI = weight (kg) ÷ height (m)², using the standard WHO adult classification: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obese.
How it works
BMI is calculated as:
BMI = weight (kg) ÷ height (m)2
For imperial units: BMI = 703 × weight (lb) ÷ height (in)2. The standard adult categories are: under 18.5 underweight, 18.5 to 24.9 normal weight, 25 to 29.9 overweight, and 30 or above obese.
How to use the BMI Calculator
Choose metric or imperial units, enter your height and weight, and read the result with the category shown below it. Try a second set of figures only when you want to compare a realistic change.
BMI is a screening measure, not a diagnosis. Age, muscle mass, pregnancy and other health factors can affect what the number means, so speak with a qualified health professional if you are concerned.