BMI Calculator
Use your own numbers after reviewing the formula and worked example.
Quick answer
Body mass index relates weight to height squared and does not directly measure body fat or health.
Formula or method
Keep units, percentages and time periods consistent. The formula is useful as a transparent check on the calculator result and helps explain why changing one input changes the answer.
Step-by-step
- Use the correct unit system.
- Square height.
- Divide weight by squared height.
- Apply 703 for pounds/inches.
Worked example
At 150 lb and 68 inches, BMI is about 22.8.
How to interpret the result
BMI is a screening measure and can misrepresent body composition for some individuals.
When the answer is used for a purchase, loan, payroll decision, construction order, school grade, health estimate or other real-world choice, verify the assumptions that matter in that context. Accurate arithmetic still depends on accurate inputs.
Common mistakes
- Using feet instead of inches in the US formula.
- Forgetting to square height.
- Treating BMI as a diagnosis.
Authoritative reference
BMI is a screening measure; adult category interpretation should not be treated as a diagnosis.
Frequently asked questions
Does BMI measure body fat?
No.
Can muscular people have high BMI?
Yes.
Is the adult formula used for children?
Children are generally interpreted with age- and sex-specific growth references.