BMI Calculator
Enter your weight and height in kilograms and centimetres, or in pounds, feet and inches, and the calculator gives your body mass index, the adult category it falls in, BMI Prime and the weight range that would give a BMI from 18.5 up to just under 25 at your height. It also shows how far you are from that range. Everything runs in your browser and nothing you type is sent anywhere.
| Category | BMI |
|---|---|
| Underweight | under 18.5 |
| Normal weight | 18.5 to under 25 |
| Overweight | 25 to under 30 |
| Obesity class I | 30 to under 35 |
| Obesity class II | 35 to under 40 |
| Obesity class III | 40 and over |
BMI is weight in kilograms divided by height in metres squared, or 703 times pounds divided by inches squared. The categories are the adult cut-offs used by the World Health Organization. BMI is a screening number for adults. It does not measure body fat or muscle, and it can mislead for athletes, older adults, children and some ethnic groups. It is not a diagnosis, so talk to a health professional about your own health. Your numbers stay in your browser.
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Math & MoneyAbout the BMI Calculator
Body mass index is your weight in kilograms divided by your height in metres squared. A person who weighs 70 kg and is 175 cm tall has a BMI of 70 / (1.75 x 1.75), which is 22.9. In pounds and inches the formula is 703 x pounds / inches squared. The adult categories used by the World Health Organization are underweight below 18.5, normal weight from 18.5 to 24.9, overweight from 25 to 29.9, and obesity from 30, which is split into class I (30 to 34.9), class II (35 to 39.9) and class III (40 and over). BMI Prime is the BMI divided by 25, so a value above 1 means a BMI above the top of the normal range. The healthy weight range is found by turning the formula around: the weight for a BMI of 18.5 and for a BMI of 25 at your height. BMI is a quick screening number for adults. It does not measure body fat, it cannot tell muscle from fat, and the cut-offs can mislead for athletes, older adults, children and some ethnic groups. It is not a diagnosis, so use it as one input and talk to a health professional about your own health.
How is BMI calculated?▾
Divide your weight in kilograms by your height in metres squared. At 70 kg and 175 cm the BMI is 70 divided by 3.0625, which is about 22.9. With pounds and inches, multiply the weight by 703 and divide by the height in inches squared.
What is a healthy BMI?▾
For adults the World Health Organization calls a BMI from 18.5 to 24.9 normal weight, below 18.5 underweight, from 25 to 29.9 overweight and 30 or more obese. These are population cut-offs and they are not a verdict on one person.
Is BMI accurate for athletes?▾
Often not. Muscle weighs more than fat, so a muscular person can have a BMI in the overweight range with a low body fat share. BMI is a screening tool and it does not measure body composition.
Does this work for children?▾
No. For children and teenagers BMI is compared with growth charts for their age and sex, and the adult categories here do not apply. Use the charts your doctor or national health service provides.
Is my data uploaded?▾
No. The calculation runs in your browser and nothing you enter is sent anywhere.