How it's calculated
BMI divides your weight by the square of your height. Because height is squared, small height differences move the result more than most people expect — which is why accurate measurement matters.
Example: 70 kg ÷ (1.75 m)2 = 70 ÷ 3.0625 ≈ 22.9 → Normal weight
The standard adult categories are: underweight below 18.5, normal weight 18.5–24.9, overweight 25–29.9, and obese 30 or above. The calculator also shows your personal healthy weight range for your height, so you can see how far you are from it in either direction.
Frequently asked questions
What is BMI?
Body Mass Index (BMI) is a screening measure that relates your weight to your height: weight in kilograms divided by height in metres squared. It places adults into four broad categories: underweight (below 18.5), normal weight (18.5–24.9), overweight (25–29.9) and obese (30 and above).
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered the healthy range. The lowest health risks are generally seen in the middle of this range, but ideal weight also depends on muscle mass, age, sex and body composition.
Is BMI accurate?
BMI is a useful population-level screening tool, but it cannot distinguish muscle from fat. Athletes and very muscular people can score as overweight, while some people with a normal BMI carry excess body fat. Treat it as one signal among several, not a diagnosis.
How is BMI different from body fat percentage?
BMI uses only height and weight, while body fat percentage measures how much of your weight is actually fat tissue. Two people with the same BMI can have very different body compositions. Body fat percentage (measured with calipers, smart scales or DEXA scans) gives the fuller picture.
Disclaimer: BMI is a screening tool, not a medical diagnosis. It does not account for muscle mass, bone density or body composition. If your result concerns you, speak with a qualified health professional. Calculator results are estimates for education only.
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