BMI calculator
Enter your weight and height to get your body mass index, your category according to the WHO, and the healthy weight range for your height. Works in pounds and feet or in kilograms and centimeters.
Enter your weight and height to calculate your BMI.
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How it is calculated
- Formula
—- With your values
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A general reference
BMI does not tell muscle from fat, and it does not consider your age, sex, or health history. It is not a diagnosis: if you have questions about your weight, talk to a health professional.How to use it
- Choose your units: imperial (pounds, feet, and inches) or metric (kilograms and centimeters).
- Enter your weight and your height. In metric you can type centimeters (175) or meters (1.75). If you like, add your age: under 18, BMI is read differently.
- Read your BMI, your category, and your position on the scale. The tool also shows the healthy weight range for your height.
- If your weight is outside that range, you will see how many pounds or kilograms separate you from it. Remember that BMI is only a general reference.
Frequently asked questions
How is BMI calculated?
Divide your weight in kilograms by your height in meters squared. A person who weighs 70 kg and is 1.75 m tall has a BMI of 70 ÷ 1.75² = 22.9. In pounds and inches the formula is 703 × weight ÷ height². For example, 154 lb at 69 in gives 703 × 154 ÷ 69² = 22.7.
What is a healthy BMI?
According to the WHO and the CDC, a BMI from 18.5 to 24.9 is in the healthy weight range. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or more is obesity, which is divided into three classes.
Does BMI work for children and teens?
Not with these ranges. Under 18, BMI is compared with percentiles for age and sex. This tool shows you the number, but a pediatrician should interpret it.
Why are there Asia-Pacific criteria?
Some Asian populations have a higher metabolic risk at a lower BMI, so the WHO suggests different cutoffs: overweight from 23 and obesity from 25. You can turn them on in the options.
What are the limits of BMI?
It does not tell muscle from fat, and it does not show where fat is stored. A very muscular person can have a high BMI without excess fat. Use it as a guide, not as a diagnosis.
Are my weight and height saved?
No. The calculation happens in your browser. This tool does not store your data and does not put it in the page link.
What is body mass index
BMI relates weight to height to give a quick idea of whether an adult is in a weight range linked to lower or higher health risk. It is calculated as weight (kg) ÷ height (m)².
WHO categories for adults
- Under 18.5: underweight (mild, moderate, or severe thinness).
- 18.5 to 24.9: normal weight.
- 25 to 29.9: overweight.
- 30 or more: obesity class I (30 to 34.9), class II (35 to 39.9), and class III (40 or more).
Example
At 5 ft 9 in, the healthy weight range goes from about 125.3 lb (BMI 18.5) to 168.6 lb (BMI 24.9). A person who weighs 180 lb has a BMI of 26.6, which is overweight, and is about 11.4 lb above the top of the normal range.
How to read it
BMI does not measure body fat and does not tell muscle apart from fat. Age, sex, body composition, and health history all matter. If you have any doubt about your weight, talk to a health professional. To compare other numbers, try the age calculator or the percentage calculator.
Updated on September 29, 2026