What is the US Navy body fat method?

The US Navy method estimates body fat percentage from circumference measurements using a logarithmic formula. Developed by Hodgdon and Beckett at the Naval Health Research Center in 1984 and validated against hydrostatic (underwater) weighing.

Is this body fat calculator completely free?

Yes. No registration, no account, and no payment required.

Do I need an account to use this calculator?

No. Open the page and start entering measurements immediately. Nothing is stored or uploaded.

How accurate is the Navy body fat method?

The method has a margin of error of approximately ±3–4 percentage points, comparable to skinfold caliper measurements and more practical than DEXA or hydrostatic weighing.

Body fat calculator

Body fat calculator is a health tool that estimates body fat percentage using the US Navy circumference method. It needs only a flexible tape measure (neck and waist for men, plus hip for women), reports lean mass alongside fat percentage, and assigns your fitness category. The tool runs in your browser.

Sex

Units

Neck (cm)

Waist (cm)

Height (cm)

Measure neck below larynx, waist at narrowest point (usually above navel).

Dedicated pages

Sex-specific and method-specific body fat calculators.

Body fat calculator for men

Estimate body fat percentage for men using the US Navy circumference method. Enter neck, waist and height. Free. Runs in your browser.

Body fat calculator for women

Estimate body fat percentage for women using the US Navy circumference method. Enter neck, waist, hip and height. Free. Runs in your browser.

Navy body fat calculator

Calculate body fat percentage using the official US Navy circumference method. Separate inputs for men and women. Free. Runs in your browser.

How to measure body fat with the Navy method

Select your sex, men need three measurements, women need four.
Measure your neck, waist, and (for women) hips with a flexible tape measure.
Enter your height to complete the formula inputs.
Your estimated body fat percentage and category appear instantly.

Common uses

Tracking body composition changes during a cutting or bulking phase alongside a calorie calculator
Assessing fitness level without expensive lab equipment alongside your BMI
Checking whether you meet US Navy or military body fat standards

Technical specification

Algorithm or formula: US Navy circumference method (Hodgdon & Beckett, 1984, Naval Health Research Center). Men: %BF = 86.010 · log10(waist − neck) − 70.041 · log10(height) + 36.76. Women: %BF = 163.205 · log10(waist + hip − neck) − 97.684 · log10(height) − 78.387.
Browser API or library: Native Math.log10. No external library.
Input limits: Numeric measurements in cm or inches. Imperial values are converted internally before the log-arithmetic.
Output: Body-fat percentage, lean-mass percentage, and the ACE category (essential, athlete, fitness, acceptable, obese).
Known limitations: Population-derived formula validated mainly against US service personnel aged 18 to 55. Margin of error roughly ±3 to 4 percentage points versus hydrostatic weighing. Tape placement accuracy materially affects the result.

Frequently asked questions

What is the US Navy body fat method?: The US Navy method estimates body fat percentage from circumference measurements using a logarithmic formula. Developed by Hodgdon and Beckett at the Naval Health Research Center in 1984 and validated against hydrostatic (underwater) weighing.
Is this body fat calculator completely free?: Yes. No registration, no account, and no payment required.
Do I need an account to use this calculator?: No. Open the page and start entering measurements immediately. Nothing is stored or uploaded.
How accurate is the Navy body fat method?: The method has a margin of error of approximately ±3–4 percentage points, comparable to skinfold caliper measurements and more practical than DEXA or hydrostatic weighing.

Reviewed and tested May 25, 2026.