BMI Calculator (Body Mass Index)

Enter your height and weight to calculate your Body Mass Index (BMI). Choose between US (imperial) or metric units — input your height in feet/inches or centimeters and weight in pounds or kilograms — and get your BMI value along with your BMI category (Underweight, Healthy Weight, Overweight, or Obese). The chart breaks down where your BMI falls across all ranges.

Disclaimer: This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any health-related decisions.

Unit System *

ft
in
lbs
cm
kg

Results

Your BMI

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BMI Category

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Healthy Weight Range (min)

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Healthy Weight Range (max)

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Results Table

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Frequently Asked Questions

What is BMI and what does it measure?

BMI (Body Mass Index) is a numerical value calculated from your height and weight. It provides a simple screening measure of body fatness for most adults. A higher BMI generally correlates with higher levels of body fat, though it is not a direct measure of body fat percentage.

What are the BMI categories for adults?

For adults 20 and older, BMI is interpreted using fixed weight categories: Underweight is below 18.5, Healthy Weight is 18.5–24.9, Overweight is 25.0–29.9, Obesity (Class I) is 30.0–34.9, Obesity (Class II) is 35.0–39.9, and Severe Obesity is 40.0 or higher.

How is BMI calculated?

In metric units, BMI is calculated as weight (kg) divided by height (m) squared. In imperial units, the formula is weight (lbs) × 703 divided by height (inches) squared. Both formulas produce the same result when units are consistent.

What are the limitations of using BMI?

BMI does not directly measure body fat and can misclassify individuals. Athletes with high muscle mass may show a high BMI despite low body fat. Older adults may have a healthy BMI but excess body fat. It also does not account for where fat is distributed in the body, which can be a significant health factor.

Is this BMI calculator suitable for children and teens?

No — this calculator is designed for adults aged 20 and older. For children and teens aged 2–19, BMI is interpreted differently using age- and sex-specific percentiles. The CDC provides a dedicated Child and Teen BMI Calculator for younger individuals.

Does BMI differ by age or sex for adults?

The standard adult BMI scale applies the same ranges regardless of age or sex. However, research suggests that the health risks associated with a given BMI may vary slightly between men and women and across different ethnic groups. Always consult a healthcare provider for a complete health assessment.

What should I do if my BMI is outside the healthy range?

If your BMI falls outside the 18.5–24.9 healthy range, it is worth discussing with a healthcare provider. They can evaluate other health indicators alongside your BMI, such as waist circumference, blood pressure, and cholesterol levels, to give a fuller picture of your health.

How accurate is an online BMI calculator?

Online BMI calculators are mathematically accurate as long as you enter your correct height and weight. The calculation itself is straightforward. However, BMI is just one health screening tool — it should be considered alongside other clinical measurements and your personal health history.