Is BMI accurate for athletes?

BMI is a general indicator and can overestimate body fat in muscular people. Use it as a guideline alongside other measures.

How is BMI calculated?

BMI is weight in kilograms divided by height in meters squared (kg/m²) — or the imperial equivalent using pounds and inches. It's a simple ratio, not a direct measurement of body fat.

What are the standard BMI categories?

Under 18.5 is considered underweight, 18.5–24.9 is a typical healthy range, 25–29.9 is overweight, and 30+ is classified as obese, according to WHO reference ranges — though individual health context always matters more than the category alone.

Does BMI account for age or sex?

The standard adult BMI categories used here are the same across sexes and most adult ages, though children and teens use different age- and sex-specific BMI percentile charts, which this calculator isn't built for.

Should I use BMI as my main measure of health?

No — treat it as one general reference point among many. It doesn't capture body composition, fitness level, or overall health, so it's best considered alongside other measures and, for personal health decisions, a conversation with a healthcare provider.

Health & Fitness Cluster

BMI Calculator

Calculate your Body Mass Index & category.

TL;DR: BMI Calculator is a free, browser-based tool that lets you calculate your Body Mass Index & category.

Units

Weight (kg)

Height (cm)

Understanding the BMI Calculator

BMI (Body Mass Index) Calculator evaluates body weight relative to height according to official World Health Organization (WHO) and CDC clinical classification categories (Underweight, Normal weight, Overweight, Obese Class I, II, III).

How It Works

Select your preferred measurement units: Metric (kg & cm) or Imperial (lbs, feet & inches).
Enter your Weight and Height.
Select Age and Biological Sex for CDC percentile context.
View your exact BMI score, visual health category gauge, and recommended healthy weight range.

Mathematical Formula & Methodology

Here is the standard mathematical equation used to calculate this result accurately:

\text{BMI} = \frac{\text{Weight (kg)}}{[\text{Height (m)}]^2} = \frac{\text{Weight (lb)} \times 703}{[\text{Height (in)}]^2}

Formula Variables Explained:
Classifies body weight into WHO categories: Underweight (<18.5), Healthy (18.5–24.9), Overweight (25–29.9), and Obese (30+).

Step-by-Step Worked Example

A person weighing 72 kg at 1.78 m height: $\text{BMI} = \frac{72}{1.78^2} = \frac{72}{3.1684} = 22.72 \text{ (Healthy Weight)}$

How to Get the Best Results

WHO Clinical Classifications: Underweight: <18.5 | Normal Weight: 18.5–24.9 | Overweight: 25.0–29.9 | Obese: 30.0+.
Limitation for Athletes: BMI measures weight mass rather than body composition; muscular athletes may register as 'overweight' despite low body fat.
Pair with Waist Circumference: Measure waist circumference alongside BMI for a more accurate assessment of visceral cardiovascular risk.

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All processing runs locally inside your browser using JavaScript and HTML5 APIs. Your data, files, and inputs are never uploaded to any remote server. Complete privacy by design.

Frequently Asked Questions

: BMI is a general indicator and can overestimate body fat in muscular people. Use it as a guideline alongside other measures.
: BMI is weight in kilograms divided by height in meters squared (kg/m²) — or the imperial equivalent using pounds and inches. It's a simple ratio, not a direct measurement of body fat.
: Under 18.5 is considered underweight, 18.5–24.9 is a typical healthy range, 25–29.9 is overweight, and 30+ is classified as obese, according to WHO reference ranges — though individual health context always matters more than the category alone.
: The standard adult BMI categories used here are the same across sexes and most adult ages, though children and teens use different age- and sex-specific BMI percentile charts, which this calculator isn't built for.
: No — treat it as one general reference point among many. It doesn't capture body composition, fitness level, or overall health, so it's best considered alongside other measures and, for personal health decisions, a conversation with a healthcare provider.

Cite This Tool

Referencing this tool in a paper, article, or bibliography? Copy a ready-made citation below.

NexLove.org. (2026). BMI Calculator [Software]. https://nexlove.org/tools/bmi-calculator.html

“BMI Calculator.” NexLove.org, 2026, nexlove.org/tools/bmi-calculator.html.

NexLove.org (2026) BMI Calculator. Available at: https://nexlove.org/tools/bmi-calculator.html (Accessed: 2026).

@misc{nexlove_bmi_calculator,
  title = {BMI Calculator},
  author = {{NexLove.org}},
  year = {2026},
  url = {https://nexlove.org/tools/bmi-calculator.html}
}

Embed This Tool

Add the live BMI Calculator tool to your own website with this snippet — it loads the real, working tool in an iframe, not a static screenshot.

<iframe src="https://nexlove.org/embed/bmi-calculator.html" width="100%" height="600" style="border:1px solid #e2e8f0;border-radius:12px" title="BMI Calculator — NexLove.org" loading="lazy"></iframe>

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