Health
BMI calculator
Body mass index is weight divided by height squared. This page is for adults 20 and older. For ages 2 to 19, use the CDC Child and Teen BMI Calculator, which uses BMI-for-age percentiles. It is a screening number, not a diagnosis, and it is a poor fit for children and for many athletes.
What this means
- A BMI of 22.9 falls in the Healthy weight adult category used by the CDC.
- For this height, the healthy weight range (BMI 18.5 to 24.9) is about 56.7 kg to 76.3 kg.
- BMI does not see muscle, fat distribution, age, or pregnancy. It is not for children. It is not medical advice.
What if
About this calculator
What this calculator does
It computes adult body mass index and the weight range that matches BMI 18.5 to 24.9 at the height you enter. You can use metric or imperial units. Imperial inputs are converted with exact factors before the formula runs.
How it is calculated
BMI is weight in kilograms divided by height in meters squared:
BMI = kg / m^2
Pounds convert as 1 lb = 0.45359237 kg. Inches convert as 1 in = 0.0254 m. The common US form, 703 times pounds divided by inches squared, is the same relationship with rounded 703. Categories follow the CDC adult cutoffs and use your exact, unrounded BMI: under 18.5 underweight, 18.5 to under 25 healthy weight, 25 to under 30 overweight, 30 or higher obesity (class 1 is 30 to under 35, class 2 is 35 to under 40, class 3 is 40 or higher). BMI is shown to one decimal. When rounding to one decimal would cross a cutoff, for example an exact 18.49 that would round to 18.5, it is shown to two decimals so the number and the category agree.
How to read the result
The healthy range is the weight, at this height, that lands on BMI 18.5 and BMI 24.9. It is a wide band on purpose. A result outside it is a reason to talk with a clinician, not a diagnosis.
Limits
Do not use this for children, and treat it cautiously for athletes, older adults, and during pregnancy. BMI does not measure body fat directly. This is an educational estimate, not medical advice. BMI does not diagnose a health condition.
Sources and method
BMI = kg / m^2 with exact pound and inch factors. CDC adult categories from the exact, unrounded BMI. Shown to one decimal, or two when rounding would cross a cutoff.
Questions
Is BMI medical advice?
No. It is an educational screening number for adults. It does not diagnose a condition.
Can I use this for a child?
No. Children need age-specific growth charts. This page uses adult cutoffs only.
Why can an athlete have a high BMI?
Muscle weighs more than the formula can see. BMI does not separate muscle from fat.
Which unit system is more accurate?
Neither. Imperial entries are converted with exact international factors, then the same formula runs.
What is the healthy weight range?
It is the weight that produces BMI 18.5 and the weight that produces BMI 24.9 at your height. Those are the edges of the CDC healthy weight range for adults.