BMI Calculator Formula
Calculate Body Mass Index (BMI) using the formula weight/(height^2). Evaluate BMI in metric and imperial units with the math expression evaluator.
Detailed Explanation
BMI Formula
Body Mass Index (BMI) is a simple measure of body fat based on weight and height. The formula depends on the unit system.
Metric Formula
BMI = weight_kg / (height_m ^ 2)
Example: A person weighing 75 kg who is 1.75 m tall:
75 / (1.75 ^ 2) = 75 / 3.0625 = 24.49
Imperial Formula
BMI = (weight_lbs / (height_in ^ 2)) * 703
Example: 165 lbs, 5'10" (70 inches):
(165 / (70 ^ 2)) * 703 = (165 / 4900) * 703 = 23.67
BMI Categories
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 - 24.9 | Normal weight |
| 25.0 - 29.9 | Overweight |
| 30.0 and above | Obese |
Converting Height
If your height is in feet and inches, convert to total inches first:
total_inches = feet * 12 + inches
For 5 feet 8 inches: 5 * 12 + 8 = 68 inches.
Then: (150 / (68 ^ 2)) * 703 = 22.81
Converting cm to m
If height is in centimeters:
75 / (175/100)^2 = 75 / 3.0625 = 24.49
Limitations
BMI does not account for muscle mass, bone density, age, or sex. It is a screening tool, not a diagnostic measure.
Use Case
A health-conscious individual quickly checking their BMI by plugging weight and height into the evaluator without needing a dedicated BMI calculator app.