Calculate Body Mass Index from height and weight with category classification and healthy range guidance.
Type your weight in pounds or kilograms.
Type your height in feet/inches or centimeters.
See your BMI score and which health category it falls into.
You enter weight in kilograms or pounds and height in centimeters, meters, feet, or inches. The tool computes BMI as weight divided by height squared, then shows the World Health Organization category (underweight, normal, overweight, obese) and a weight range that would put you in the normal category for your height. A common surprise: for short people, a few pounds change the category quickly; for tall people, a large weight change may not. BMI is a screening index, not a direct measure of body fat.
A concrete input and expected output from the current implementation.
Input
weight: 70 kg, height: 1.75 m
Expected output
BMI = 22.9 kg/m² (normal weight). Healthy weight range for 1.75 m: 56.7 to 76.6 kg.
BMI is 70 divided by 1.75 squared, which is 70 / 3.0625 = 22.857, rounded to 22.9. The upper end of the displayed range (76.6 kg) corresponds to a BMI of 25.0, which is the boundary between normal and overweight per the WHO cutoffs. The lower end (56.7 kg) corresponds to a BMI of 18.5, the boundary between underweight and normal. The tool may use these boundary values for the range rather than 24.9 exactly.
You choose metric or imperial units. The tool converts pounds to kilograms (1 lb = 0.45359237 kg) and inches to meters (1 in = 0.0254 m) before computing. Height can be entered as total inches or feet plus inches, depending on the input fields. The calculation itself only ever uses kilograms and meters internally.
The index is the ratio of weight in kilograms to the square of height in meters. The result is rounded to one decimal place. Using the WHO cutoffs, under 18.5 is underweight, 18.5 to 24.9 is normal, 25.0 to 29.9 is overweight, and 30.0 or above is obesity. The tool also lists the weight range that maps to the normal category for the given height.
No. The WHO categories are population-level screening thresholds, not diagnoses. A BMI of 26 falls in the overweight band, but in a fit person with high muscle mass it may not imply excess fat. Conversely, a normal BMI does not guarantee metabolic health, so medical advice should look beyond this single number.
It computes the same BMI number, but the interpretation is different. For children and teens aged 2 to 19, doctors use BMI percentile for age and sex, because body composition changes during growth. Using adult normal ranges on a growing child can misclassify their status. Use the CDC or WHO child growth charts for that context.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
Calculate percentages, percentage change, and what percent one number is of another with step-by-step breakdowns.
Calculate tips and split bills between multiple people with customizable tip percentages and rounding options.
Calculate monthly payments, total interest, and generate amortization schedules for loans and mortgages.
Calculate sale prices, savings amounts, and final costs after single or stacked percentage discounts.
Compute mean, median, mode, standard deviation, variance, and other descriptive statistics from a data set.
Convert between fractions, decimals, and percentages instantly with simplification and step-by-step work.