BMI Calculator
Body Mass Index from height and weight (adult screening tool).
BMI is a screening measure only. For personal health advice, speak with a qualified professional.
Guide: BMI Calculator
Compute Body Mass Index (BMI) from height and weight with this BMI calculator. BMI is a population-level screening metric for adults; it does not measure body fat directly and should not replace medical advice. It remains popular because it needs only a scale and a tape measure, which makes it a reasonable first checkpoint before deeper clinical tests.
How BMI is calculated
BMI equals weight in kilograms divided by height in meters squared. We accept height in centimeters and convert internally.
Categories such as underweight, normal, overweight, and obesity ranges are general WHO-style bands for screening conversations.
Because BMI scales with height squared, small height entry errors change the index more for shorter individuals—double-check measurements.
Limitations everyone should know
Athletes with high muscle mass may read “high” without excess fat. Older adults may have different risk profiles at the same BMI.
Speak with a clinician about waist circumference, blood work, and activity when assessing health.
Ethnicity and body-composition norms can shift risk thresholds in clinical guidelines; online calculators show generic bands only.
What to do after a result
Trend your BMI over months alongside waist, strength gains, and energy levels rather than reacting to a single day’s weight fluctuation.
Nutrition and exercise changes should be gradual and personalized, especially if you have chronic conditions or take medications that affect weight.