BMI Calculator – Imperial / English
BMI Calculator – Metric
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).
| 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.
BMI Table (pounds and inches)
BMI Table (metric)
More Resources
- World Health Organization – BMI Classification
- Slate – Beyond BMI – Why doctors won’t stop using an outdated measure for obesity
- Wikipedia – Body mass index
- National Institute of Health – Accuracy of Body Mass Index to Diagnose Obesity in the US Adult Population
- National Heart Lung and Blood Institute – Assessing Your Weight and Health Risk
- BBC News Health – Where are you on the global fat scale?