Last updated on June 27th, 2024

Body Mass Index is an easy way of calculating the weight status of an individual by using his or her height and weight. The formula is BMI = kg/m2. In this, kg is an individual’s weight in kilograms and m2 is the square of their height (in units of meter square). A BMI of 25.0 or above is considered overweight, while the healthy limit is between 18.5 and 24.9. BMI calculation is applicable to most adults in the age groups 18 to 65 years.

body mass index calculator

Calculate Your Body Mass Index With the Help of a BMI Calculator

The calculation of BMI is similar in both adults and kids. The calculation depends upon the following formulas:

Meters and Kilograms (or centimeters)

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

The BMI formula is weight (in kgs) divided by height (in meters squared). As, the common units for height is centimeters, divide height in cms by 100 to get height in meters.

For instance: Weight = 70 kg, Height = 163 cm (1.63 m)

Calculation: 70 ÷ (1.63)2 = 26.41

Body Mass Index Calculator
Units for measurement Formula and Calculation
Inches and Pounds Formula: weight (lb) / [height (in)]2 x 703

The BMI calculation is done by dividing weight (in pounds) by height (in inches squared). This is multiplied by a conversion factor of 703.

Example: Weight = 150 lbs, Height = 5’5″ (65″)

Calculation: [150 ÷ (65)2] x 703 = 24.96

BMI Introduction

The body mass index (BMI) is a physical assessment for measuring a person’s total amount of body fat. Its invention was done by Belgian polymath Adolphe Quetelet in the 1800s. Hence, it is at times also called as the Quetelet index.

The BMI is expressed as kg/m2. The BMI calculations determine whether a person is underweight, healthy, overweight or obese. BMI might be used as a screening tool; however, it does not identify the body fatness or health of a person. To depict whether BMI is a health risk, a doctor carries out some additional evaluations as well. These evaluations can be dietary measurements, skinfold thickness assessments, evaluations of exercises, and family history.

BMI Calculator

BMI Calculator

BMI Calculator

BMI Chart for Adults

Below is a graph of BMI classes accumulated by the WHO data. The dashed lines characterize subdivisions within a chief classification.

Understanding the Levels Of BMI

For adults with age 20 years or above, BMI interpretation is done using standard weight status classes. These classes are similar for males and females of all age groups and body types.

BMI Ranges are:

Body Mass Index Range Chart
BMIWeight Status
Below 18.5Underweight
18.5 to 24.9Healthy Weight
25.9 to 29.9Overweight
Above 29.9Obese

For instance, below are the ranges of weight, their BMI values, and the weight status classes for an individual whose height is 5′ 9″.

HeightWeight (in lbs)BMIWeight Status
5′ 9″124 or lessUnder 18.5Underweight
 125 to 16818.5 to 24.9Healthy Weight
 169 to 20225.0 to 29.9Overweight
 203 lbs or above30 or moreObesity

Body Mass Index Calculation Formula

BMI Calculator or Body Mass Index Calculator

These are some equations used for computing BMI in the International System of Units (SI) and the US customary system (USC) for a person with a height of 5'10" and a weight of 160 pounds.

Limitations of BMI Calculator

  • BMI differs with a person’s age, sex, and race. Consequently, a person’s BMI can only be compared to people of similar sex, age, and race.
  • Disabled or elderly individuals have less muscle mass. Hence, they would have a lower BMI. This would not imply that their weight would be normal or underweight.
  • BMI fails to distinguish between fat and muscle. Hence, it might underestimate a few and overestimate others. For instance, an athlete might have a high BMI due to a higher amount of muscle instead of fat.
  • Moreover, pregnant females might have a higher BMI due to augmented weight related to pregnancy, but not essential because of increased fat. BMI would overestimate body fat in such instances.
  • BMI also fails to distinguish between body fat distribution. Fat around the waist (with a body shape like an apple) is considered more dangerous as compared to that around the hips (i.e., pear body shape).

In conclusion, BMI considers natural variations in body shape, offering a healthy weight range for a specific height. Thus, doctors might take other factors into consideration along with BMI measurements while evaluating whether a person has a healthy weight.