How Do I Calculate My BMI?

Medically Reviewed on 10/9/2020

BMI is a way to determine if a person is underweight, normal weight, overweight or obese.
BMI is a way to determine if a person is underweight, normal weight, overweight or obese.

Body mass index (BMI) is a measurement of body fat based on height and weight. The formula for calculating BMI is given in Table 1 or you can use the body mass index calculator below.

Maintaining a healthy weight offers the following health benefits:

Table 1. The Formula for Calculating BMI
Measurement Units Formula and Calculation
Kilograms and meters (or centimeters)

Formula: weight (kg) / height (m)2

The formula for BMI is weight in kilograms divided by height in meters squared. If height has been measured in centimeters, divide by 100 to convert this to meters.

Pounds and inches

Formula: 703 x weight (lbs) / height (in)2

When using English measurements, pounds should be divided by inches squared. This should then be multiplied by 703 to convert from lbs/inches2 to kg/m2.

Example: If a person weighs 65 kg and the person’s height is 165 cm (1.65 m), the BMI is calculated as 65 ÷ (1.65)2 = 23.87 kg/m2, which means that the person has a BMI of 23.87 kg/m2 and is considered to have a healthy weight.

When calculating in pounds and inches, if a person weighs 120 lbs and the person’s height is 5 feet 6 inches (66 inches), the BMI is calculated as 703 x 120/(66)2 = 19.3 kg/m2, which means that the person has a BMI of 19.3 kg/m2 and is considered to have a healthy weight.

BMI Calculator

To use this calculator:

  1. The default BMI of 16.6 shown on the tool is for a 5'5" person who weighs 100 lbs.
  2. Use the switch on top to pick either metric or imperial measurements.
  3. Set the height and weight dials to match your own height and weight.
  4. View your BMI number at the center of the tool and see where you fall on the obesity chart.

BMI values are based on clinical data about averages for these measurements across a wide swath of people.

The body mass index (BMI) is used to assess your weight relative to your height. This BMI calculator allows you to easily screen yourself for obesity or extra, unhealthy weight. If your results from the calculator aren't in the healthy range, don't worry too much. People with muscular builds may be classified as obese, even with a low body fat percentage and optimum health, simply because the BMI formula uses only two data points.

What is the body mass index (BMI)?

Body mass index (BMI) is a person’s weight in kilograms divided by the square of height in meters. It indicates the amount of body fat.

BMI is the most inexpensive screening tool to measure body fat. Although it does not directly measure body fat, it can be correlated with a more direct measure of body fat.

The various categories of BMI include

  1. BMI values less than 18.5 kg/m2 are considered underweight
  2. BMI values between 18.5 kg/m2 to 24.9 kg/m2 are healthy
  3. BMI values between 25 kg/m2 to 30 kg/m2 are overweight
  4. BMI values greater than 40 kg/m2 are considered obese

What is the ideal BMI?

The ideal weight has been mentioned in Table 2.

Table 2. Ideal Weight in lbs According to Height
Height Minimal risk
(BMI under 25 kg/m2)
 

Moderate risk
(BMI 25–29.9 kg/m2)
Overweight

 

High risk
(BMI 30 kg/m2 and above)
Obese

4'10'' 118 or less 119–142 143 or more
4'11'' 123 or less 124–147 148 or more
5'0'' 127 or less 128–152 153 or more
5'1'' 131 or less 132–157 158 or more
5'2'' 135 or less 136–163 164 or more
5'3'' 140 or less 141–168 169 or more
5'4'' 144 or less 145–173 174 or more
5'5'' 149 or less 150–179 180 or more
5'6'' 154 or less 155–185 186 or more
5'7'' 158 or less 159–190 191 or more
5'8'' 163 or less 164–196 197 or more
5'9'' 168 or less 169–202 203 or more
5'10'' 173 or less 174–208 209 or more
5'11'' 178 or less 179–214 215 or more
6'0'' 183 or less 184–220 221 or more
6'1'' 188 or less 189–226 227 or more
6'2'' 193 or less 194–232 233 or more
6'3'' 199 or less 200–239 240 or more
6'4'' 204 or less 205–245 246 or more

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Medically Reviewed on 10/9/2020
References
Medscape Medical Reference

American Heart Association


CDC