Calculate your Body Mass Index (BMI) online with our free BMI Calculator. Computes WHO weight classifications (Underweight, Normal, Overweight, Obese), ideal healthy weight range targets, BMI Prime ratios, and Ponderal Index density with 100% offline privacy in Metric and Imperial units.
Choose Metric (kg, cm) or Imperial (lbs, ft, in) units.
Type in your weight and height values into the input fields.
View your computed BMI score, WHO gauge meter position, and ideal weight target range.
Uses official World Health Organization weight threshold boundaries for accurate health assessment.
Calculates exact minimum and maximum weight bounds needed to maintain a healthy $18.5 \to 24.9$ BMI score.
All calculations execute locally in browser memory. Height and weight data are never stored or logged.
Body Mass Index (BMI) is an epidemiological screening index evaluated by dividing body mass by the square of body height. In metric units: \(\text{BMI} = \frac{\text{mass (kg)}}{\text{height (m)}^2}\). In imperial units: \(\text{BMI} = \frac{\text{mass (lbs)}}{\text{height (in)}^2} \times 703\).
The World Health Organization (WHO) classifies adult scores into four primary bands: Underweight (\( < 18.5 \)), Normal Weight (\(18.5 \le \text{BMI} \le 24.9\)), Overweight (\(25.0 \le \text{BMI} \le 29.9\)), and Obese (\( \ge 30.0 \)).
To position the visual needle smoothly along the color-coded gauge, the calculator applies piecewise linear interpolation across threshold intervals, mapping BMI values onto percentage offsets from \(0\%\) (\(\text{BMI} = 15.0\)) to \(100\%\) (\(\text{BMI} = 40.0\)).