The Navy Body-Fat Formula: How the Tape Test Actually Works

Q: Is the Navy formula the same as the old Army tape test?

The 2023 Army one-site test used a different abdominal-only regression. The Navy circumference formula (neck + waist, + hip for women) is the common secondary method across several services.

Step-by-step through the circumference formula most branches use for the secondary body-fat evaluation — with the exact equations.

By The VivMetric Editorial Team · independent editorial research project

The measurements

Height (inches), neck circumference just below the Adam’s apple, waist at the navel (men and women), and hip at its widest point (women only). Measurements are taken with a snug but not compressed tape.

The equations

Men: 495 ÷ (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450. Women: 495 ÷ (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450.

Where it fits in 2026

The formula is now the secondary evaluation: WHtR < 0.55 passes outright; at or above the gate, the service estimates body fat with this method and checks it against the age/sex table. DoD 1308.03 caps the corridor at 18–26% (men) / 26–36% (women) by branch and age.

Run the Navy formula now

Estimate body-fat % with the exact U.S. Navy circumference formula (neck + waist; hips for women).

Sex

Height (in)

Neck (in)

Waist at navel (in)

Result

Estimated body-fat %17.5%

±3–4% versus DXA. Women must include hip. This is the Navy method used as a cross-branch estimate; your service runs its own official assessment.

About this calculator

Estimates body-fat percentage with the U.S. Navy circumference method, using neck (and waist; hips for women) measurements.

The formula

Navy method: men BF% ≈ 86.010·log10(waist−neck) − 70.041·log10(height) + 36.76; women add a hip term. Keep units consistent (inches or cm).

Frequently asked questions

Q: How accurate is it?

A: Typically ±3–4 percentage points versus a DXA scan. Treat it as an estimate, not a lab measurement.

Q: Why include hip for women?

A: The Navy formula uses hip circumference for female measurements to account for fat distribution.

Q: What is a healthy range?

A: Roughly 10–20% for men and 18–28% for women is considered fit; your service uses its own official tables.

How to read the result

A circumference estimate is a model rather than a measurement. The Navy equation was derived by fitting tape readings against a reference method across a large sample, so it reproduces the average relationship rather than the composition of any single person. Expect roughly three to four percentage points of error against a laboratory standard, and expect that error to grow for anyone whose fat distribution sits far from the average the equation was built on.

Technique moves the result more than most people expect. The neck tape goes below the larynx and slopes downward at the front, the waist tape sits at the navel, and for women the hip tape is taken at the widest point. A single inch of error on the neck measurement shifts the estimate by about a percentage point, which is how the same person can be measured twice and receive two different answers. Track change over time with one method and treat a comparison between two different methods as meaningless.

Quick answers

Is the Navy formula the same as the old Army tape test?