BMI Calculator
Inputs
Tab to move between fields
Results
Your BMI
24.4
Identify Input Parameters
4 parameters
= Unit System = 0, Weight = 170lbs, Height (feet) = 5ft, Height (inches) = 10in, Weight = 170lb, Height = 70in
= 6 input(s) provided
Calculate Your BMI
Your BMI
= 24.4
= 24.4
Calculate Category
= Normal weight
= Normal weight
Calculate Healthy Weight Min
= 128.9 lbs
= 128.9 lbs
Body mass index
- 1.Convert height to metres
The index is defined in kilograms per square metre, so centimetres have to go first.
- 2.Square the height
Squaring rather than cubing is a deliberate approximation: body mass grows faster than height but slower than volume would suggest. It is also the index's main known weakness — it systematically reads high for tall people and low for short ones.
- 3.Divide mass by squared height
The result is a mass per unit area — a single number comparable across body sizes.
Adolphe Quetelet proposed weight divided by height squared while studying the statistical distribution of human measurements — he was describing populations, not diagnosing individuals. Ancel Keys coined the name 'body mass index' 137 years later, and noted in the same paper that it was only adequate as a population measure.