# BMI Calculator

LAST UPDATE: September 24th, 2020

## Formula – How to Calculate BMI

In pounds and inches, BMI is calculated as:

(Mass in lbs ÷Heigh in inches2) x 703
In meters and kilograms, BMI is calculated as:

Mass in kg ÷ Heigh in m2

### Example

Example 1:
A person has a mass of 165 lbs and is 5 foot 10 inches (70 inches) tall.

BMI = (165 ÷ 702) x 703

BMI = (165 ÷ 4900) x 703

BMI = 0.3367 x 703

BMI = 23.67

This person’s BMI is 23.67

Example 2:
A person has a mass of 75kg and is 1m 78cm (1.78m) tall.

BMI = 75 ÷ 1.782

BMI = 75 ÷ 3.1684

BMI = 23.67%

BMI = 23.67

This person’s BMI is 23.67

## Definition – What is BMI?

BMI, or “Body-Mass Index” is a ratio of a person’s height to weight.
It provides a simple number to evaluate whether a person is underweight (below 18.5), ideal weight (18.5 – 25), overweight (25 – 30), or obese (above 30).

### Challenges with BMI

BMI was initially intended to be an objective measurement of larger populations instead of individuals.
Because of its simplicity and ease to measure, it has become common in medical and health fields to monitor BMI along with other variables.
BMI is not an absolute “score” – it is merely an indicator.
Some challenges with BMI include:
– It does not show a difference between people with lots of muscle and lots of fat – a very muscly person may have the same BMI as a person with a lot of fat.
– It does not show a difference between body types that may hold weight in different parts of their bodies
It is important to remember that BMI is an indicator and not an absolute measurement of health.