BMI Calculator

Key features

• Metric (cm + kg) or imperial (feet + inches + lbs) input — values are converted internally with exact factors.
• BMI shown to one decimal and classified with the standard adult bands: under 18.5, 18.5–24.9, 25–29.9 and 30+.
• Colour-coded gauge from 10 to 40 with a marker showing where your BMI sits between the bands.
• Healthy weight range for your exact height (BMI 18.5–24.9), expressed in kg or lbs.
• Updates live as you type, with an on-screen note spelling out what BMI does and doesn't account for.

How it works

1. 1

   Choose your units

   Switch between the Metric and Imperial tabs; each keeps its own set of fields.

2. 2

   Enter height and weight

   Centimetres and kilograms, or feet plus inches and pounds — the result recalculates on every keystroke.

3. 3

   Read your BMI and band

   The large number is your BMI; the badge underneath labels it Underweight, Healthy weight, Overweight or Obese.

4. 4

   Check the gauge and range

   A marker shows where you sit on the 10–40 scale, and the line below lists the weight range that would put you in the healthy band for your height.

Tips for better results

• 💡The healthy-range figure is often the most useful output — it turns an abstract index into a concrete weight target, or reassurance that you're already in range.
• 💡BMI is a screening tool: it can't tell muscle from fat and it ignores bone density, age and ethnicity — the tool itself carries this caveat.
• 💡For children and teens, age- and sex-specific percentile charts are the norm; this calculator is built for adults.
• 💡Switching tabs doesn't convert your entry for you — each unit system keeps its own values, so re-enter the measurement in the other system.

Frequently asked questions