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Calculate your Body Mass Index (BMI) from height and weight using metric or imperial units and view the corresponding adult BMI range.
The BMI ranges shown here are intended for adults ages 20 and older. People ages 2–19 require age- and sex-specific BMI interpretation.
Your BMI range and information will appear here.
Body Mass Index (BMI) is a screening measure that relates an adult's weight to their height. It provides a numerical value that can be compared with commonly used adult BMI ranges. BMI is simple to calculate, but it should be interpreted as a screening measure rather than a complete assessment of health or body composition. The displayed categories follow the CDC convention for adults ages 20 and older.
When weight is measured in kilograms and height is measured in meters, BMI is calculated using the following formula: BMI = weight (kg) ÷ height² (m²). For example, an adult who weighs 70 kg and is 1.75 meters tall would have a BMI of approximately 22.9: BMI = 70 ÷ (1.75 × 1.75) ≈ 22.9. ToolXone's metric mode accepts height in centimeters, so the calculator converts the entered height to meters before calculating BMI.
When weight is entered in pounds and height is measured in inches, the BMI formula used by this calculator is: BMI = [weight (lb) ÷ height² (in²)] × 703. ToolXone's Feet / Pounds mode allows height to be entered as feet and inches. The calculator converts the height to total inches before applying the formula. The factor 703 is the conventional rounded conversion factor used in the customary-unit BMI formula.
This calculator groups adult BMI results into four ranges: Underweight — Below 18.5; Healthy Weight Range — 18.5 to below 25; Overweight — 25 to below 30; Obesity Range — 30 or higher. These are screening categories for adults ages 20 and older. “Healthy Weight Range” names a BMI category; it does not establish that an individual is healthy.
Height: Measure without shoes, standing upright with both feet flat and weight evenly distributed. Look straight ahead and remove anything on top of your head that interferes with the measurement. Use a height-measuring device with a horizontal headpiece resting on top of the head.
Weight: Measure without shoes. Stand centrally on the scale with your hands at your sides and wait until the reading is stable.
Enter height and weight in the units shown beside the selected inputs.
Choose Metric if you want to enter height in centimeters and weight in kilograms. Choose Feet / Pounds if you want to enter height in feet and inches and weight in pounds. Enter your measurements and select Calculate BMI. The calculator displays your BMI rounded to one decimal place, the corresponding adult BMI range, and a visual marker showing where the result falls on the calculator's BMI scale. The category is determined from the unrounded BMI, while the displayed number is rounded to one decimal place. Near a boundary, the display can equal that boundary while the underlying value remains below it. For example, BMI 24.96 displays as 25.0 but remains in the Healthy Weight Range.
BMI compares weight with height and provides a convenient screening value. It can be useful for looking at weight-related categories at a general level because the calculation requires only height and weight. However, BMI does not directly measure body fat and does not explain why a person has a particular weight. The same BMI value can occur in people with different body compositions.
BMI uses only height and weight. It does not distinguish between body fat, muscle, bone and other components of body mass. As a result, two adults with the same height and weight can have the same BMI while having different body compositions. BMI also does not directly measure fitness, nutrition, body-fat distribution or overall health. For these reasons, the result should be treated as a screening value rather than a diagnosis or complete health assessment.
This calculator displays categories for adults ages 20 and older. For people ages 2–19, BMI requires interpretation relative to age and sex using BMI-for-age percentiles. This calculator does not provide that interpretation.
Equivalent metric and customary-unit measurements produce approximately the same BMI. Small differences can arise from the rounded factor 703 and from rounding the entered measurements. Very near a category boundary, those differences can place the results in different categories. If you need to convert a weight measurement before using a calculator, ToolXone's Weight Converter can help convert between common weight units.
Use the result to understand which adult BMI range corresponds to the height and weight entered. Avoid interpreting the number as a complete description of health, fitness or body composition. If an individual health assessment is needed, factors beyond BMI may need to be considered by an appropriately qualified healthcare professional.
These sources support the BMI formulas, adult screening categories, interpretation and measurement guidance described above. Their inclusion does not imply endorsement of ToolXone.