BMI Calculator: Body Mass Index for Adults
By Hesaplayıcı
The BMI calculator divides your weight by the square of your height to find your body mass index. Enter your weight and height in metric units, in pounds or in stones. It rates the result with the World Health Organization's adult classification and shows the healthy weight range for your height. It is for adults and is not medical advice.
Worked example: An adult of 68 kg and 170 cm
Body mass index
23.5 kg/m²
- Healthy weight range: from
- 53.5 kg
- Healthy weight range: to
- 72 kg
Step by step
Body mass index
BMI = weight / height²
BMI = 68 / 1.7² = 23.5 kg/m²
Healthy weight range: from
healthy weight from = 18.5 × height²
healthy weight from = 18.5 × 1.7² = 53.5 kg
Healthy weight range: to
healthy weight to = 24.9 × height²
healthy weight to = 24.9 × 1.7² = 72 kg
How to use
- Choose your Units: Metric (kg, cm), Pounds (lb; ft, in) or Stones (st, lb; ft, in).
- Enter your Weight in kilograms, in pounds, or in stones and pounds.
- Enter your Height in centimetres, or in feet and inches.
- Press Calculate. The result shows your BMI, your category and the healthy weight range.
Formula
BMI = weight (kg) / height (m)²Healthy weight range = 18.5 × height (m)² to 24.9 × height (m)²
Weight is your body weight in kilograms. Height is your height in metres; the calculator divides centimetres by 100. With pounds or stones, it converts first: 1 lb = 0.45359237 kg, 14 lb to a stone, 1 in = 2.54 cm, 12 in to a foot; the healthy weight range is then in pounds. The BMI is rounded to one decimal. The WHO adult categories are: below 18.5 underweight, 18.5–24.9 normal, 25.0–29.9 overweight, 30.0 or more obesity.
Worked example
The worked example on this page shows an adult who weighs 68 kg and is 170 cm tall. The steps give the BMI and the lower and upper end of the healthy weight range for that height; the result shows the WHO category.
Limits
BMI does not tell muscle, fat and bone apart, so the same BMI can mean different things for different builds. Children and teens use percentiles by age and sex, and BMI is not read in pregnancy. Waist size and other risk factors are not taken into account. The result is not medical advice; ask your doctor about decisions on your weight.
Frequently Asked Questions
What is a normal BMI?
In the WHO adult classification, 18.5 to 24.9 is normal. 25.0–29.9 is overweight and 30.0 or more is obesity.
How is BMI calculated?
Your weight in kilograms is divided by the square of your height in metres. The calculator rounds the result to one decimal and uses that value for the category.
Is BMI valid for children?
This calculator is for adults of 18 or older only. For children and teens, BMI is read on percentile charts by age and sex.
Can I enter my weight in pounds and my height in feet?
Yes. Choose Pounds or Stones under Units, then enter your weight and your height in feet and inches. The calculator converts them to kg and m and shows the healthy weight range in pounds.
Does BMI tell me everything about my health?
No. BMI does not tell muscle, fat and bone apart; it is a screening measure. Ask your doctor for an assessment.
Calculation rules
- BMI = weight (kg) / height (m)². The categories are the World Health Organization (WHO) adult classification: below 18.5 underweight, 18.5–24.9 normal, 25.0–29.9 overweight, 30.0 or more obesity.
- The BMI is rounded to one decimal and the category uses that value. The healthy weight range is the weight at a BMI of 18.5 and of 24.9 for your height, rounded to 0.1 kg.
- For adults of 18 or older only. Children and teens use percentiles by age and sex; BMI is not interpreted in pregnancy.
- BMI does not tell muscle, bone and fat apart. The result is not medical advice; ask your doctor about decisions on your health.