BMI Calculator

Units

Weight kilograms (kg) Enter a valid weight greater than 0.

Height centimetres (cm) Enter a valid height greater than 0.

Your BMI

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How to Use This Tool

Choose your preferred unit system — metric (kg/cm) or imperial (lbs/in).
Enter your weight and height in the selected units.
Click Calculate BMI to see your Body Mass Index and weight category.
Use the category result as a general screening indicator, not a full health assessment.

What Is BMI and How Is It Calculated?

Body Mass Index (BMI) is a simple calculation using your height and weight to estimate whether you're in a healthy weight range. The metric formula is:

BMI = weight (kg) ÷ height (m)²

In imperial units, the formula is adjusted with a conversion factor: BMI = 703 × weight (lbs) ÷ height (in)².

BMI Categories (WHO Classification)

Below 18.5: Underweight
18.5 – 24.9: Normal weight
25 – 29.9: Overweight
30 and above: Obese

Limitations of BMI

BMI is a population-level screening tool, not a diagnostic measure. It doesn't distinguish between muscle and fat mass, so athletes and muscular individuals often show a higher BMI despite having low body fat. It also doesn't account for fat distribution, age, or sex-specific differences in body composition. For a fuller picture, BMI is best used alongside other measures like waist-to-hip ratio or body fat percentage.

Why BMI Is Still Useful

Despite its limitations, BMI remains widely used by healthcare providers as a fast, free, and reasonably reliable first-pass indicator of weight-related health risk across large populations, which is why it continues to be a standard part of routine health checkups worldwide.

Frequently Asked Questions

Is BMI accurate for everyone?

BMI is a useful general screening tool but has known limitations for athletes, older adults, and pregnant women, since it does not distinguish muscle mass from fat mass. Consult a healthcare professional for a fuller assessment.

What is a healthy BMI range?

According to the WHO classification, a BMI between 18.5 and 24.9 is considered a healthy or normal weight range for most adults.

Does BMI differ for men and women?

The standard BMI formula itself does not differentiate by sex, though body composition and healthy fat ranges can differ between men and women — which is a key limitation of using BMI alone.

This calculator is provided for general informational and estimation purposes only. Results should not be treated as professional financial, tax, legal, medical, or engineering advice. Always verify critical calculations with a qualified professional or official source before making decisions.