BMI Calculator

Calculate Body Mass Index in metric or imperial units.

What Does the BMI Calculator Do?

The BMI Calculator computes your Body Mass Index from height and weight — in metric (kg/cm) or imperial (lb/ft-in) units — and shows your WHO weight category along with the healthy weight range for your height. BMI is weight divided by height squared (kg/m²), the screening measure used worldwide by health services to flag potential weight-related risk.

How to Calculate Your BMI

  1. Choose metric or imperial units with the tabs.
  2. Enter your weight and height.
  3. Click Calculate BMI — your index, category and healthy range appear, with your bracket highlighted in the reference table.

Reading the Result

  • Below 18.5 — underweight.
  • 18.5 – 24.9 — the healthy reference range.
  • 25.0 – 29.9 — overweight.
  • 30.0 and above — obesity.

BMI is a population-level screening tool, not a diagnosis. It cannot distinguish muscle from fat — athletes often score "overweight" while lean — and it doesn't capture fat distribution, which matters for health risk. Treat your number as a conversation starter, and combine it with waist measurement, fitness and medical advice for the full picture.

Frequently Asked Questions

What is the BMI formula?

Weight in kilograms divided by height in meters squared: BMI = kg / m². For imperial units the equivalent is 703 × lb / in². The calculator applies the conversion automatically.

Is BMI accurate for athletes?

Often not — muscle is denser than fat, so muscular people frequently land in the "overweight" band while carrying little fat. For athletic builds, body-fat percentage and waist circumference are more informative.

Does the same scale apply to children?

No. Child and teen BMI is interpreted against age-and-sex percentile charts, not the fixed adult thresholds this calculator uses. Pediatric growth charts are the right tool under 18.

What does the healthy weight range mean?

It is the weight span that would put your BMI between 18.5 and 24.9 at your height — a target band, not a single "ideal" number. Where you sit best within it depends on build and muscle.