BMI calculator
Calculate your body mass index from height and weight. Pick units independently for each input — mix kg with inches, lb with cm. Compare WHO, South Asian, and East Asian thresholds.
Midpoint is the middle of the healthy BMI range for your height. It's a reference value, not a medical target — healthy weight varies by individual.
About the BMI calculator
This BMI calculator works out your body mass index from your height and weight, with a twist: each input has its own unit toggle. You can enter your height in centimeters and your weight in pounds, or your height in feet and inches and your weight in kilograms — whatever combination matches how you actually think about your measurements. The tool recalculates instantly as you type, showing your BMI value, which category you fall into, and the healthy weight range for your height.
How BMI is calculated
BMI uses a simple formula: BMI = kg / m². Take your weight in kilograms and divide it by the square of your height in meters. A person who weighs 68 kg and stands 1.70 m tall has a BMI of 68 / (1.70 × 1.70) = 23.5. For imperial units, the equivalent formula is BMI = (lb / in²) × 703. The math is standardized worldwide — the same formula is used by every health organization and clinical setting on the planet.
Why multiple threshold sets?
The original WHO BMI categories were developed from studies of predominantly European populations. Research over the past two decades has shown that health risks associated with a given BMI level are not uniform across ethnic groups. South Asian populations tend to accumulate more visceral fat at lower BMI values, meaning metabolic conditions like type 2 diabetes can appear at a BMI that would be considered "normal" under WHO standards. The South Asian cutoffs (normal up to 23, overweight 23–27.5) reflect guidelines adopted by medical bodies in India, Pakistan, and Bangladesh. Similarly, East Asian populations — particularly in Japan, China, and South Korea — face elevated cardiovascular risk at lower BMI thresholds, leading to adjusted categories (normal up to 24, overweight 24–28). This calculator lets you switch between all three sets so you can see how your BMI reads under the thresholds most relevant to your background.
What BMI doesn't tell you
BMI is a screening tool, not a diagnosis. It measures weight relative to height but cannot distinguish between muscle and fat. Athletes with high muscle mass often classify as "overweight" by BMI while being metabolically healthy. Conversely, someone with a "normal" BMI can carry excess visceral fat — sometimes called "skinny fat" — and face elevated health risks. BMI also doesn't account for age, sex, bone density, or fat distribution. For older adults, a slightly higher BMI is often associated with better outcomes. For a fuller picture, clinicians use BMI alongside waist circumference, body fat percentage, blood markers, and clinical history.