On this page
The steps
Metric (cm and kg)
- Convert height to meters: divide by 100.
- Square it.
- Divide weight by that number and round to one decimal place.
Imperial (feet, inches and pounds)
- Convert height to inches: feet × 12, plus inches.
- Square it.
- Multiply weight by 703.
- Divide and round to one decimal place.
Tips
- Keep enough decimals. For metric, keep at least four decimal places in the squared height to get the BMI right.
- Use (a + b)² for squaring. 67² = 60² + 2 × 60 × 7 + 7² = 4,489. More shortcuts.
- Round only at the end. Rounding early can change the last digit.
Frequently asked questions
How exact do my answers need to be?
Within about 0.1 for the BMI. Whole-number steps like inches and the 703 product need to be exact.
Where can I get problems on paper?
Use the worksheet generator to print a set with an answer key.
Sources
Kept up to dateLast updated October 9, 2026
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This page is for education and is not medical advice. Talk with a healthcare professional about your weight and health.
