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Body Composition calculator

Body Fat
Calculator

Estimate body fat percentage with the U.S. Navy circumference method. Use recent body measurements for a clearer body-composition estimate.

Start Body Fat Explore Body Composition
100% privateInstant resultsNo sign-up
1Enter your details

Calculate your result

Use realistic, recent measurements for the most useful estimate.

Sex used by this formula
100% privateInputs stay in this browserInstant resultsCalculated in real timeNo sign-upFree to use
2Your result
Body FatREADYStart with the form

Your result will appear here

Complete the form and select “Calculate result.” Your measurements never leave this page.

Educational estimate only—not medical advice.
Understand your result

How your Body Fat estimate is created

A transparent overview of the inputs, method, and appropriate interpretation.

Evidence-informed Browser based
How it works

About this Body Fat estimate

It combines height and selected body circumferences to estimate body-fat percentage, then derives related fat-mass or lean-mass values when needed. Consistent tape placement matters more than chasing a single reading.

Circumference-based body composition method
Body measurements→Circumference model=Estimated Body Fat
  1. 01Enter details
  2. 02Review inputs
  3. 03Use the estimate
Private by designNo account requiredInputs are not stored
Common questions

Body Fat Calculator FAQ

Clear answers to help you understand and use your estimate.

01Is the Body Fat Calculator free and private?

Yes. It is free, runs in your browser, requires no account, and does not store the measurements you enter.

02Can I use this result as medical advice?

No. This result is an educational estimate, not a diagnosis or treatment recommendation. A qualified professional can interpret it within your complete health and training context.

03Why might my Body Fat result differ from a real-world result?

Tape placement, breathing, hydration, recent meals, body-fat distribution, and the population used to develop the equation can change the estimate.

04How often should I recalculate Body Fat?

Recalculate when you take a new set of circumference measurements. Use the same tape positions and measurement conditions for a useful comparison.

Read our calculation methodology →Still have questions? Explore the guides ↗