How to calculate your BMI
- Choose your units: kilograms and centimeters, or pounds, feet and inches.
- Enter your weight and your height.
- See your BMI, your category and the healthy weight range for your height.
- If the result worries you, talk to a health professional.
What is body mass index?
BMI relates weight to height: you 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 ÷ (1.75 × 1.75) = 22.9.
The World Health Organization classifies adults like this: below 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight and 30 or more is obesity. The healthy weight range shown by the tool is the one that gives a BMI between 18.5 and 24.9 for your height.
It is a quick way to get your bearings, but it has limits: it doesn't tell muscle from fat, or how weight is distributed in the body. A very muscular athlete can come out as overweight without being so.
Things to keep in mind
- It is meant for adults aged 18 or older; for children and teenagers, growth charts by age and sex are used.
- It is not a diagnosis and does not replace a medical or nutritional consultation.
- Results are rounded to one decimal place.
Frequently asked questions
How is BMI calculated?
You divide your weight in kilograms by your height in meters squared. With 70 kg and 1.75 m: 70 ÷ 3.0625 = 22.9.
What is a normal BMI?
Between 18.5 and 24.9 according to the World Health Organization, for adults.
Does it work for children or teenagers?
No. For people under 18, BMI is compared against growth charts by age and sex.
Why does my BMI say overweight if I play sports?
Because BMI doesn't tell muscle from fat. A person with a lot of muscle mass can have a high BMI without excess body fat.
Is my data saved?
No. Everything is calculated in your browser and nothing is sent anywhere.