# Body Fat Estimate Calculator

> Body fat calculator: estimate your body fat percentage from simple body measurements using the US Navy method, with lean mass. Free, private, no signup.

- **Canonical URL:** https://boringtoolskit.com/body-fat-calculator/
- **Category:** Health
- **Evidence level:** authored-methodology
- **Reviewed:** July 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

U.S. Navy circumference method: men %BF = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76; women use waist, neck, and hip terms.

## Worked example

A 69-inch person with 15-inch neck, 34-inch waist: about 31% body fat by the Navy method.

## Assumptions

- The named U.S. Navy circumference equations are used with inch measurements.
- Measurements must follow a consistent tape-placement protocol.
- The estimate is not a clinical diagnosis and may be inaccurate for individuals outside the source population.
- This tool provides general estimates for planning and education only; it is not medical advice and not a substitute for a qualified healthcare professional.
- Always consult your doctor or another healthcare provider about your specific situation.

## Common questions

### How does the body fat calculator work?

It uses measurements like height, neck, waist, and hip to estimate body fat percentage with established formulas. Just enter your numbers in the browser—no signup required.

### Is this body fat calculator accurate?

It provides a close estimate using the U.S. Navy method, ideal for tracking trends over time. For precise clinical results, consult a professional.

### Do I need to create an account to use it?

No, the body fat calculator is completely free and browser-based with no signup needed. Simply open the page and input your measurements.

## Related tools

- /bmi-calc/
- /calorie-calc/
- /age-calculator/

## Sources

- [Guide 4 Body Composition Assessment](https://www.mynavyhr.navy.mil/Portals/55/Support/Culture%20Resilience/Physical/Guide%204-%20Body%20Composition%20Assessment%20(BCA)%20(MAR%202023).pdf)
- [About adult BMI (context and limitations of screening measures)](https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html)

---

*Local planning estimate. Verify current terms, rates, and policies before acting.*