What is a healthy BMI?

A BMI of 18.5–24.9 is the normal-weight range for most adults.

How do I calculate BMI by hand?

Divide weight in kilograms by height in metres squared, or multiply weight in pounds by 703 and divide by height in inches squared.

Is BMI accurate for muscular people?

No — BMI can't tell muscle from fat, so athletes often read "overweight." Pair it with a body-fat estimate.

Is BMI different for men and women?

The formula and adult cut-offs are the same; body-fat percentage differs by sex and is a better individual measure.

What's a healthy weight for my height?

The calculator shows the weight range that puts you at BMI 18.5–24.9 for your height.

BMI Calculator

Use this BMI calculator to find your body mass index from your height and weight, see which WHO category it falls in, and read the healthy weight range for your height — in metric or imperial units.

How BMI is calculated

Body mass index is your weight divided by the square of your height. In metric units it is BMI = weight (kg) ÷ height (m)². The imperial form is equivalent: BMI = 703 × weight (lb) ÷ height (in)². This tool converts everything to kilograms and metres and computes a single value.

Worked example

Someone who is 5'10" (1.778 m) and weighs 170 lb (77.1 kg): BMI = 77.1 ÷ 1.778² = 77.1 ÷ 3.16 = 24.4, which is in the Normal weight band.

BMI categories

BMI	Category
Below 18.5	Underweight
18.5 – 24.9	Normal weight
25.0 – 29.9	Overweight
30.0 – 34.9	Obese (class I)
35.0 – 39.9	Obese (class II)
40.0 and above	Obese (class III)

Source: World Health Organization adult BMI classification.

What BMI doesn't tell you

BMI is a quick population-level screen, not a body-composition measurement. It can't distinguish muscle from fat, so very muscular people can read "overweight" while carrying little fat. It also ignores where fat is stored, and is less reliable for older adults, pregnancy, and some ethnic groups. For a fuller picture, pair it with the Body Fat Percentage Calculator and the Waist-to-Hip Ratio Calculator.

Frequently asked questions

What is a healthy BMI?: A BMI of 18.5–24.9 is the normal-weight range for most adults.
How do I calculate BMI by hand?: Divide weight in kilograms by height in metres squared, or multiply weight in pounds by 703 and divide by height in inches squared.
Is BMI accurate for muscular people?: No — BMI can't tell muscle from fat, so athletes often read "overweight." Pair it with a body-fat estimate.
Is BMI different for men and women?: The formula and adult cut-offs are the same; body-fat percentage differs by sex and is a better individual measure.
What's a healthy weight for my height?: The calculator shows the weight range that puts you at BMI 18.5–24.9 for your height.

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Disclaimer. BMI is an estimate for screening healthy adults and is not a diagnosis or a substitute for professional medical advice.