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BMI Calculator

Calculate your Body Mass Index and see your category.

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How to Calculate BMI Online

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About This Tool

Free BMI calculator online — calculate your Body Mass Index from your height and weight and instantly see your WHO weight category: Underweight (BMI < 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), or Obese (30+). Supports both metric (kg / cm) and imperial (lbs / feet & inches). BMI is the most widely used screening tool for weight assessment in healthcare and public health. Doctors, fitness coaches, and individuals use it to assess weight relative to height and identify potential health risks associated with being underweight or overweight. The tool also shows the healthy weight range for your height so you know your target window.

How to Use

  1. 1

    Select your unit system

    Choose Metric (kg, cm) or Imperial (lbs, feet & inches).

  2. 2

    Enter your weight and height

    Input your current weight and height.

  3. 3

    Read your BMI

    See your BMI score, weight category, and the normal weight range for your height.

Frequently Asked Questions

What is a healthy BMI?+
According to WHO guidelines, a BMI of 18.5–24.9 is considered healthy (Normal weight). Under 18.5 is Underweight, 25–29.9 is Overweight, and 30+ is Obese.
Is BMI accurate for athletes?+
BMI has limitations — it does not distinguish between muscle and fat. Athletes with high muscle mass may have a high BMI while being very lean. It is a screening tool, not a diagnostic one. Consult a doctor for a full health assessment.
How is BMI calculated?+
BMI = weight (kg) ÷ height² (m). In imperial: BMI = (weight in lbs × 703) ÷ height² (in inches).

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