BMI Calculator

Calculate Body Mass Index
This free online bmi calculator runs in your browser and is part of our Calculators collection.

BMI Calculator

Calculate your Body Mass Index

BMI Categories:

  • Underweight: BMI less than 18.5
  • Normal weight: BMI 18.5 - 24.9
  • Overweight: BMI 25 - 29.9
  • Obese: BMI 30 or greater
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Instant In-Browser Execution Runs locally in JavaScript without wait times or server delays.
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100% Privacy & Security Your inputs and files are never stored or logged on remote servers.
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Cross-Device Responsive Fully optimized for mobile smartphones, tablets, and desktop displays.
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100% Free Forever No subscription fees, no signups, and no software installations.

How to Use the Online BMI Calculator

1 Select Unit System (Metric or Imperial)

Choose Metric (Centimeters & Kilograms) or Imperial (Feet, Inches & Pounds).

2 Enter Height & Weight

Type your exact height and body weight into the input fields.

3 Inspect Calculated BMI & WHO Category

View your Body Mass Index score and visual classification needle: Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), or Obese (≥30).

4 Review Ideal Healthy Weight Range

Inspect the recommended minimum and maximum healthy weight span tailored to your height.

Frequently Asked Questions

Common questions about using this free online bmi calculator.

What is the formula used to calculate BMI? ▾
In metric: `BMI = Weight (kg) / (Height (m))^2`. In imperial: `BMI = (Weight (lbs) / (Height (inches))^2) × 703`.
What are the World Health Organization (WHO) BMI classifications? ▾
Underweight: BMI less than 18.5; Normal weight: BMI 18.5 to 24.9; Overweight: BMI 25.0 to 29.9; Obesity Class I: BMI 30.0 to 34.9; Obesity Class II: BMI 35.0 to 39.9; Obesity Class III: BMI 40 or greater.
Does BMI account for muscle mass in athletes? ▾
BMI is a statistical population screening tool based on total weight and height. It does not distinguish between body fat and lean muscle mass, so bodybuilders and muscular athletes may register as "overweight" despite low body fat.
What is considered a healthy weight for my height? ▾
A healthy weight corresponds to a BMI between 18.5 and 24.9. The calculator displays this exact healthy target weight range below your results.

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