# BMI Calculator

LAST UPDATE: April 8th, 2018

## How to Calculate BMI

In pounds and inches, BMI is calculated as:
$\frac{\text{Mass(lbs)}}{\text{Height (inches)}^2}\times703$
In meters and kilograms, BMI is calculated as:
$\frac{\text{Mass (kg)}}{\text{Height (m)}^2}$

## Example

Example 1:
A person has a mass of 165 lbs and is 5 foot 10 inches (70 inches) tall.
$\text{BMI}=\frac{165}{70^2}\times703$
$latex\text{BMI}=\frac{165}{4900}\times703$
$latex\text{BMI}=0.3367\times703$
$latex\text{BMI}=23.67$
This person’s BMI is 23.67
Example 2:
A person has a mass of 75kg and is 1m 78cm (1.78m) tall.
$\text{BMI}=\frac{75}{1.78^2}$
$\text{BMI}=\frac{75}{3.1684}%$latex \text{BMI}=23.67%
This person’s BMI is 23.67

## 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).

Category BMI Range
Very severely underweight less than 15.0
Severely underweight 15.0 – 16.0
Underweight 16.0 – 18.5
Healthy weight 18.5 – 25
Overweight 25.0 – 30.0
Moderately obese 30.0 – 35.0
Severely obese 35.0 – 40.0
Very severely obese more than 40.0

## 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.