BMI Calculator

Calculate your Body Mass Index based on height and weight. See where you fall on the WHO classification scale.

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BMI Formula
BMI = weight (kg) / height (m)2
Imperial: BMI = (weight in lbs × 703) / (height in inches)2

Enter Your Details

Your BMI
Classification
18.5 – 24.9
Healthy BMI Range
Healthy Weight Range
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How This BMI Calculator Works

This calculator uses the standard BMI formula adopted by the World Health Organization. For imperial units, it multiplies weight in pounds by 703 and divides by the square of height in inches. For metric units, it divides weight in kilograms by the square of height in meters.

Understanding BMI Categories

Underweight (below 18.5): May indicate insufficient body weight. Can be associated with nutritional deficiencies and weakened immune function.

Normal weight (18.5 to 24.9): Generally associated with the lowest risk of weight-related health problems. Most adults should aim for this range.

Overweight (25 to 29.9): Weight above the normal range. May increase risk for type 2 diabetes, high blood pressure, and heart disease.

Obese (30 and above): Associated with significantly increased health risks. Further divided into Class I (30-34.9), Class II (35-39.9), and Class III (40+).

Limitations of BMI

BMI does not distinguish between muscle and fat mass. Highly muscular individuals may have a high BMI despite low body fat. BMI also does not account for fat distribution. For a more complete picture, use our Body Fat Calculator or Waist-to-Hip Ratio Calculator.

Frequently Asked Questions

What is a healthy BMI?
18.5 to 24.9 for most adults. Optimal BMI varies by age, sex, and ethnicity.
Is BMI accurate for athletes?
BMI can overestimate body fat in muscular people. Use our Body Fat Calculator for a better assessment.
Does BMI apply to children?
For ages 2-20, BMI is interpreted using CDC age- and sex-specific growth chart percentiles.

Explore More Tools

Use our Body Fat Calculator for body composition. Find target weight with Ideal Weight Calculator. For calorie needs, try the TDEE Calculator.

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