Calculate your Body Mass Index with imperial or metric units
| Underweight | < 18.5 |
| Normal weight | 18.5 - 24.9 |
| Overweight | 25.0 - 29.9 |
| Obese | ≥ 30.0 |
This BMI calculator computes your Body Mass Index — weight in kilograms divided by height in meters squared — and shows where you land on the standard WHO categories. Everything runs locally in your browser; your height and weight are never sent to a server.
Switch between imperial (feet/inches and pounds) and metric (centimeters and kilograms) with the toggle at the top, then press Calculate BMI or tap the space bar. You get your BMI to one decimal, a color-coded category, a marker on a visual scale from 10 to 40, and a reference table with your row highlighted.
Say you're 5 ft 10 in and 170 lbs. That converts to about 1.78 m and 77.1 kg, so BMI = 77.1 / (1.78 × 1.78) ≈ 24.4 — inside the normal range (18.5–24.9) but near its upper edge. Gaining about five pounds would push the same person past 25 into the overweight category, a good reminder that the cutoffs are sharp lines drawn through a continuous scale, not sudden changes in health.
Using WHO cutoffs for adults: under 18.5 is underweight, 18.5 to 24.9 is normal weight, 25.0 to 29.9 is overweight, and 30.0 or above is obese. This calculator uses exactly these ranges and highlights the one you fall into.
Not on its own. BMI doesn't distinguish muscle from fat, so muscular people can read as overweight, and it can miss low muscle mass in older adults. It's a population-level screening number, not a diagnosis — and nothing here is medical advice. Talk to a healthcare provider about what your number means for you.
The formula and the standard adult cutoffs are the same for both. For children and teens, BMI is instead interpreted with age- and sex-specific percentile charts, which this adult calculator doesn't provide.
Yes. The calculation runs entirely in your browser with JavaScript — no numbers are transmitted, logged, or stored. Refresh the page and the inputs reset.