WorldCalcs

BMI Calculator

Body Mass Index from your weight and height, with WHO adult category and healthy-weight range.

Reviewed by the WorldCalcs team · Methodology · Last reviewed: June 2026

Your BMI

22.9Normal

Healthy weight range for your height (BMI 18.5–24.9): 56.7 – 76.3 kg

WHO adult categories: Underweight < 18.5 · Normal 18.5–24.9 · Overweight 25–29.9 · Obese ≥ 30.

BMI is a general screening tool, not a diagnosis or medical advice. Talk to a healthcare professional about your health. See our Disclaimer.

What is BMI?

Body Mass Index (BMI) is a simple screening number that relates your weight to your height. It is weight in kilograms divided by height in metres squared, and it sorts adults into broad ranges: underweight, normal, overweight and obese. Health services use it as a quick first look at whether someone's weight may pose a health risk, but it is only a rough guide: it does not measure body fat directly or tell muscle from fat. This calculator gives your BMI and category in both metric and imperial units.

How BMI is calculated

The metric formula is BMI = weight (kg) divided by height (m) squared. For imperial units, BMI = 703 × weight (lb) divided by height (in) squared. The standard adult categories from the World Health Organization are: under 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, and 30 or above obese.

Example

Someone who is 70 kg and 1.75 m tall has a BMI of 70 divided by (1.75 × 1.75) = 70 divided by 3.0625 = 22.9, which is in the normal range. In imperial units, 154 lb at 5 ft 9 in (69 in) gives 703 × 154 divided by (69 × 69) = 22.7, essentially the same.

All calculations happen in your browser. Nothing is sent, stored, or tracked.

Results are estimates and may contain errors — for general information only, not professional advice. Always verify before relying on them. Disclaimer

How to use

Choose metric or imperial, then enter your weight and height. BMI updates instantly along with the category and the healthy-weight range for your height.

BMI is a screening tool, not a diagnosis. It does not separate fat from muscle and is not used for children, who use age- and sex-specific percentiles.

Frequently asked questions

What is a healthy BMI?+

For most adults a BMI between 18.5 and 24.9 is considered normal.

How is BMI calculated?+

Weight in kilograms divided by height in metres squared (or 703 × pounds divided by inches squared).

Is BMI accurate for everyone?+

No; it does not measure body fat directly and can misclassify very muscular people, older adults and some groups. See our Body Fat Calculator.

What are the BMI categories?+

Under 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, 30 or above obese.

Does BMI work the same for men and women?+

The formula and adult categories are the same; body composition differs, which is one of BMI's limitations.

Is BMI suitable for children?+

No; children use age- and sex-specific percentiles, not the adult categories.

What is the difference between BMI and body fat percentage?+

BMI uses only height and weight; body fat percentage estimates the actual proportion of fat.

How can I change my BMI?+

Through changes in weight; our BMR Calculator and Calorie Calculator help you plan that sensibly.

References

  • World Health Organization (WHO) — Body Mass Index (BMI) classification for adults.

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