How to use the BMI Calculator
Enter the information requested in the calculator and select Calculate. The result updates immediately. Review the units and assumptions before using the estimate for an important decision.
- Use consistent units for every value.
- Enter realistic figures rather than rounded guesses where possible.
- Compare the result with the explanation and verify sensitive decisions independently.
BMI Calculator formula
Body mass index divides weight in kilograms by height in metres squared.
Practical example
A person weighing 70 kg at 175 cm has a BMI of about 22.9.
Understanding the BMI Calculator
The BMI Calculator is designed to turn a practical question into a transparent calculation. Enter the requested values, review the selected units and compare the output with the formula shown above. The page explains both the arithmetic and the meaning of the result so that the number can be used with appropriate context.
Inputs, assumptions and accuracy
Treat the result as an educational screening estimate rather than a diagnosis. Individual health depends on medical history, body composition, medications, activity and other factors that a short formula cannot fully represent.
Accuracy starts with reliable inputs. A calculator can evaluate the formula precisely, but it cannot correct an inaccurate measurement, an outdated rate or an assumption that does not match the situation. Try a reasonable low and high scenario when an input is uncertain.
How to interpret the result
Read the displayed result together with its units and supporting breakdown. Small differences caused by rounding are normal. For decisions with financial, medical, legal, tax, engineering or safety consequences, compare the estimate with an authoritative source or qualified professional.
Common mistakes to avoid
- Mixing units or time periods.
- Entering a percentage as a whole number when a decimal is expected, or the reverse.
- Rounding inputs too early.
- Assuming an estimate guarantees a future outcome.
- Ignoring costs, constraints or personal factors outside the formula.
Related concepts and terms
body composition · metabolism · energy expenditure · healthy range · measurement · age · sex · height · weight · calorie balance · screening estimate · clinical guidance
Questions people ask
How to calculate BMI?
Divide weight in kilograms by height in metres squared. For US units, multiply pounds by 703, then divide by height in inches squared.
How to calculate BMI of the body?
Use measured weight and height in the BMI formula. BMI is a screening measure and does not directly measure body fat.
Are my values saved?
No. The calculation runs locally in your browser and the values are not submitted.