BMI Calculator
Calculate adult Body Mass Index from height and weight and see the matching WHO category range.
Your measurements
Enter height and weight to calculate BMI.
Your BMI
Normal
BMI Prime
0.92
Ponderal Index
13.1
Your BMI
Normal
BMI Scale
WHO adult categories
Underweight
< 18.5
Normal
18.5–24.9
Overweight
25–29.9
Obese I
30–34.9
Obese II+
35+
Estimate only — not medical adviceView details
BMI is a screening tool and does not measure body fat directly. It may not be accurate for athletes, older adults, or certain body types.
Live BMI
22.9
Normal
Prime: 0.92
How it works
Body Mass Index (BMI) is a simple screening ratio of weight to height. For adults it is typically weight in kilograms divided by height in meters squared (or an equivalent imperial formula).
Enter height and weight in the units you prefer. The calculator converts as needed, computes BMI, and places the result in commonly used WHO-style adult categories such as underweight, normal, overweight, and obesity ranges.
BMI does not measure body fat directly and does not know your muscle mass, bone structure, or where you carry weight. Athletes and some body types can land in a higher category without excess fat.
Use BMI as one quick flag among many—waist measures, fitness, labs, and clinical judgment matter more for decisions. It is especially limited for children, pregnancy, and older adults unless a clinician uses age-appropriate charts.
If you are tracking energy needs, pair BMI context with BMR, TDEE, or calorie tools. BMI alone does not say how many calories you should eat.
Frequently asked questions
- Is BMI accurate for athletes?
- Often less so. Higher muscle mass can raise BMI without excess fat. Pair BMI with other measures when possible.
- What units should I use?
- Either metric or imperial is fine—the calculator converts. Consistency matters more than which system you pick.
- Does BMI diagnose health?
- No. It is a population screening tool. Individual health depends on many factors beyond a single ratio.
- Why do category cutoffs matter?
- Cutoffs are conventions used in public health and many clinical workflows. They help compare groups, but they are not personalized medical advice.
- Should children use this adult BMI tool?
- Children and teens usually need age- and sex-specific percentile charts. Adult cutoffs are not appropriate for most pediatric screening.
Related calculators
- BMR CalculatorEstimate basal metabolic rate with Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle and map it to activity levels.
- Calorie CalculatorEstimate maintenance calories from BMR and activity, then plan deficit or surplus targets for weight goals.
- TDEE CalculatorEstimate total daily energy expenditure by combining a BMR formula with your typical activity multiplier.
- Body Fat CalculatorApproximate body fat percentage from common measurement formulas and visualize lean vs fat mass.