Calculate body mass index with metric or imperial units and interpret your BMI category quickly.
Overview
BMI is a screening metric that compares weight to height. It is widely used to identify potential underweight, healthy weight, overweight, and obesity risk bands in adults.
This BMI calculator supports US, metric, and UK-style units, then reports BMI Prime and Ponderal Index alongside WHO-style adult categories. You can also back-calculate a healthy weight interval at your current height for realistic goal setting.
BMI does not measure body fat directly and can misclassify muscular or older adults. Use it with waist measurements, activity habits, and clinical guidance when making health decisions.
Steps
Select metric (kg/cm) or imperial (lb/in).
Use your current morning weight for consistency.
Use measured standing height without shoes.
The tool applies the BMI equation instantly.
Compare result with WHO adult category cutoffs.
Use healthy BMI limits to estimate a practical goal weight.
Math
BMI = weight(kg) / height(m)^2
BMI divides mass by squared height, normalizing weight for stature so people of different heights can be compared on the same scale.
Worked cases
BMI = 70 / (1.75^2) = 70 / 3.0625 = 22.86
BMI = 22.9 (healthy range)
BMI = 86.18 / (1.778^2) = 27.26
BMI = 27.3 (overweight category)
Low = 18.5 x 1.65^2 = 50.4 kg; High = 24.9 x 1.65^2 = 67.8 kg
Healthy weight range: about 50 to 68 kg
Why use this
Questions