BMI Calculator

Calculate your Body Mass Index (BMI) in metric or imperial units.

Weight (kg)

Height (cm)

About this tool

Calculate your Body Mass Index (BMI) in seconds using metric (kg/cm) or imperial (lb/ft) measurements. The BMI calculator shows your classification - Underweight, Normal, Overweight, or Obese - and estimates a healthy weight range for your height. Used by healthcare providers worldwide as a quick screening tool for weight-related health risks.

How to Calculate Your BMI

1Select your unit system: metric (kg/cm) or imperial (lb/ft·in).
2Enter your weight and height.
3Your BMI value and classification appear instantly.
4Review the healthy weight range shown for your height.

Frequently Asked Questions

What is a healthy BMI range?+

The World Health Organisation defines a healthy BMI as 18.5–24.9. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese. These are screening thresholds, not diagnoses.

Is BMI accurate for athletes?+

BMI does not distinguish between fat and muscle mass. Athletes often have a high BMI despite low body fat. For these individuals, waist-to-hip ratio or body composition scans are more informative.

Does BMI differ for children?+

Yes. For children (2–18), BMI is assessed using age- and sex-specific percentile charts rather than fixed adult thresholds. This tool calculates adult BMI only.

What is the formula for BMI?+

BMI = weight (kg) divided by height squared (m²). In imperial: BMI = (weight in lb divided by height in inches squared) multiplied by 703.

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