BMI Calculator
Calculate your body mass index from your weight and height in metric or US units, see your WHO weight category and the healthy weight range for your height.
Runs in your browser. Nothing is uploaded.
About the BMI Calculator
Body mass index (BMI) is your weight in kilograms divided by the square of your height in metres. Doctors and health services use it as a quick screening measure, because it is simple to calculate and correlates with body fat across large groups of people.
This calculator accepts metric or US units and places the result in the World Health Organization’s adult categories: underweight below 18.5, healthy weight from 18.5 to 24.9, overweight from 25 to 29.9 and obesity from 30. It also shows the weight range that corresponds to a healthy BMI at your height. BMI does not measure body fat directly, so it can overestimate it in muscular people and underestimate it in older adults; it is a starting point for a conversation with a health professional, not a diagnosis.
How to use the BMI Calculator
- 1
Choose metric (kg and cm) or US units (lb, feet and inches).
- 2
Enter your weight and height. The BMI and category update as you type.
- 3
Compare your result with the category table and the healthy weight range for your height.
Examples
70 kg, 175 cmBMI 22.9 · Healthy weight
Healthy weight for this height: 56.7–76.3 kg200 lb, 5 ft 10 inBMI 28.7 · Overweight
Healthy weight for this height: 128.9–173.5 lbGood to know
- For adults aged 18 and over. Children and teenagers are assessed with age- and sex-specific BMI percentiles instead.
- BMI does not distinguish muscle from fat or show where fat is carried. Waist measurement and other checks give a fuller picture.
- Some health services use lower thresholds for people of Asian, Black African or other backgrounds. Ask your doctor which ones apply to you.
Frequently asked questions
How is BMI calculated?
Weight in kilograms divided by height in metres squared. For 70 kg and 1.75 m: 70 ÷ (1.75 × 1.75) = 22.9. US units are converted to metric first.
What is a healthy BMI?
For most adults, the WHO considers 18.5 to 24.9 a healthy range. Your doctor may use different targets based on your age, ethnicity or health.
Is BMI accurate for athletes?
Often not. Muscle is denser than fat, so very muscular people can have a high BMI while carrying little body fat.
Are my measurements saved?
No. The calculation runs in your browser and nothing is stored or sent.
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