BMI calculator
Body mass index from height and weight.
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How it's calculated
Body mass index is weight divided by height squared, in kilograms and metres. With pounds and inches the same ratio is multiplied by 703. The healthy weight range turns the formula around: the weights that give a BMI of 18.5 and 24.9 at your height. BMI is a screening number for adults, not a diagnosis; it says nothing about where the weight is or how much is muscle.
What do the BMI ranges mean?
For adults: under 18.5 is underweight, 18.5 to 24.9 is the healthy range, 25 to 29.9 is overweight and 30 or more is obese (CDC and WHO cut-offs). Some Asian populations use lower overweight thresholds.
Is BMI accurate for athletes or older adults?
Not very. Muscle is denser than fat, so muscular people read high; older adults with less muscle can read healthy while carrying extra fat. Waist measurement and body fat percentage fill in the picture.
Does BMI work for children?
Not with these ranges. Children and teens are assessed with age-and-sex percentile charts; ask a paediatrician or use the CDC child calculator.
Results are estimates for informational purposes only and are not financial, medical or legal advice.