How the BMI Calculator Works
Choose your unit system
Toggle between Metric (kilograms and centimeters) and Imperial (pounds, feet, and inches). The calculator automatically adjusts all labels, input fields, and placeholder values to match your selection. The toggle is clearly visible at the top of the calculator card.
Enter your weight
Type your weight into the input field. For Metric, enter your weight in kilograms. For Imperial, enter your weight in pounds. The calculator accepts values from 1 to 500 kg (or 1 to 1,100 lbs). Use whole numbers or decimals for more precise results.
Enter your height
For Metric, enter your height in centimeters (for example, 175 cm). For Imperial, enter your height using the two separate fields for feet and inches (for example, 5 feet 9 inches). The calculator converts feet and inches to total inches internally.
View your results
Your BMI is calculated instantly as you type. The results panel shows your BMI value (rounded to one decimal place), your WHO category with color coding (green for normal, yellow for overweight, red for obese), a visual gauge showing where you fall on the scale, your healthy weight range for your height, your BMI Prime (ratio to the upper normal limit of 25), and your Ponderal Index.
Copy or share your result
Click the copy button to copy your BMI result (for example, "BMI: 23.1 — Normal") to your clipboard. You can paste it into a message to your doctor, a health journal, or your personal notes.
Tips for Accurate Results
- Weigh yourself in the morning before eating, wearing minimal clothing.
- Measure your height without shoes, standing straight against a wall.
- BMI is a screening tool, not a diagnostic tool — it does not measure body fat directly.
- Athletes or people with high muscle mass may have a high BMI without excess body fat.
- For children and teenagers (under 20), BMI-for-age percentile charts should be used instead.