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BMI Calculator. And your healthy weight range.

Body mass index from weight and height, the WHO category it falls in, and the healthy weight range for your height.

Live calculation

What's your BMI?

lb
in
Body Mass Index 24.3
Category
Normal weight
Healthy range
122 lb–164 lb

weight = 72.57 kg, height = 1.727 m
BMI = 72.57 ÷ 1.727² = 24.3 (Normal weight)

Your figures are kept on this device only.

How it works

Body mass index compares weight to height using a single formula that's the same for every adult, which makes it cheap and consistent to calculate — and also its biggest weakness. BMI cannot tell the difference between muscle and fat, so it's a population screening tool, not a diagnosis of any individual's body composition.

BMI = weight (kg) ÷ height (m)²

The World Health Organization's adult categories are: under 18.5 is underweight, 18.5–24.9 is normal weight, 25–29.9 is overweight, and 30 or above is obese. These bands were derived from population health outcomes, not from any individual body type — a muscular athlete and a sedentary adult can share the same BMI with very different body fat. For a more direct estimate of body composition, see the Body Fat Percentage Calculator.

Worked example

160 lb at 5'8" (68 in).

Step by step
  1. Convert to metric: 160 lb = 72.57 kg, 68 in = 1.727 m.
  2. Square the height: 1.727² = 2.983.
  3. BMI = 72.57 ÷ 2.983 = 24.3.

A BMI of 24.3 falls in the normal weight range (18.5–24.9), close to its upper edge.

Common questions

What counts as a healthy BMI?

18.5–24.9 is the standard adult range used by the WHO and most health authorities. It's a population-level guideline rather than a personal target — the "healthy range" shown alongside your result converts that band into an actual weight range for your height, which is often easier to reason about.

Does BMI work the same way for everyone?

The formula and thresholds are the same for all adults regardless of sex, but BMI has known limitations: it tends to overestimate body fat in muscular or athletic people and can underestimate it in older adults who've lost muscle mass. It also isn't validated for children, and pregnancy changes weight in ways BMI doesn't account for.

Is BMI the same as body fat percentage?

No — BMI only uses weight and height, so it can't distinguish fat from muscle. Body fat percentage, estimated from circumference measurements, gets closer to actual body composition. See the Body Fat Percentage Calculator for that estimate.