Bmi Calculator

This tool computes Body Mass Index from height and weight, supports both metric (cm/kg) and imperial (ft/in/lb) units with automatic conversion when you switch systems, and classifies the result as Underweight, Normal, Overweight, or Obese. It also shows where your BMI sits on a 10–40 colour scale and gives your healthy weight range for a BMI of 18.5–24.9.

1. Pick the unit system: Metric or Imperial (switching converts any values you have already entered). 2. Enter Height — metric uses one cm field, imperial uses ft + in. 3. Enter Weight (kg or lb). 4. Click Calculate. Non-positive or empty values show a 'fill all fields' error toast. Reset clears the form.

BMI = weightKg / (heightM × heightM). Metric: heightM = cm/100. Imperial: heightM = (ft × 12 + in) × 0.0254 and weightKg = lb × 0.453592. Categories: Underweight < 18.5, Normal 18.5–24.9, Overweight 25–29.9, Obese ≥ 30. Healthy weight range = 18.5 × heightM² to 24.9 × heightM², reported in kg (metric) or lb (imperial). BMI is rounded to 1 decimal.