BMI looks wrong? Check centimetres, metres and the square
A 70 kg adult who is 175 cm tall has a BMI of about 22.86. One misplaced unit can change that answer by a factor of ten thousand.
BMI calculator →Follow the units through the formula
BMI divides body mass in kilograms by height in metres squared. First convert 175 cm to 1.75 m, then calculate 70 / (1.75 × 1.75) = 22.8571. The calculator asks for height in centimetres and performs that conversion internally. Enter 175 in that field, not 1.75. Converting a number correctly but entering it into the wrong field is still an input error.
Check the scale before the decimal places
Using 175 squared as the denominator gives about 0.002286, which is one ten-thousandth of the intended result. A smaller measurement mistake also matters: at 170 cm, the same 70 kg produces about 24.22. Recheck the height and the units before interpreting a change in the last decimal place. A sensible rounded display does not make uncertain measurements precise.
Use the result as a screening number
BMI does not identify how much of body weight comes from muscle, fat or fluid. Use consistent measurements and keep the unrounded value until the calculation is finished. Adult interpretation should not be applied automatically to children or pregnancy. The body-fat calculator explains another estimation method, while the conversion tool helps reconcile units. Neither turns the BMI number into an individual diagnosis.
Try the calculators
- BMI calculator
Calculate body mass index from height and weight.
- Body fat calculator
Estimate body fat from height and circumferences in metric or imperial units.
- Unit converter
Convert length, mass, area, volume, speed and data size.