Tape-measure body fat estimate

Navy Body Fat Calculator

Estimate body fat percentage with the US Navy circumference method. Enter height, neck, waist, and hip measurements to get a fast tape-test estimate without uploading a photo.

This tool is for personal fitness tracking and education. Official Navy BCA results are determined by the current Navy process, tables, and PRIMS entry.

Calculate Navy Body Fat

Choose sex, enter measurements in inches, then calculate your estimated body fat percentage.

Use a flexible tape and measure to the nearest tenth of an inch for personal tracking.
Navy method Uses the common circumference equations for men and women.
Fast inputs Only height plus tape measurements are required.
Privacy-first The calculator runs in your browser and does not upload measurements.
Clear limits Explains when tape estimates can differ from clinical tests.

How the Navy Body Fat Formula Works

The classic Navy method is a circumference-based estimate. Men use waist, neck, and height. Women use waist, hip, neck, and height. All measurements are entered in inches and the calculator applies base-10 logarithms.

Male formula
Body fat % = 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76
Female formula
Body fat % = 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387
Why it is useful: The Navy body fat calculator gives a practical body-composition estimate when you have a tape measure but no calipers, DEXA scan, or photo-based AI estimate.

Before You Calculate

Small tape-measure differences can move a Navy body fat calculation by several percentage points. Check these inputs before you trust the result.

Height

Enter total height accurately; the equation uses height in inches, not feet alone.

Waist and neck

Keep the tape level and relaxed. Do not pull it tight enough to compress skin.

Female hip input

For women, hip circumference should be taken at the widest practical point around hips and glutes.

Example Navy Method Calculations

These examples show how different circumference inputs change the result.

Male example

70 in height, 15 in neck, 34 in waist

A common athletic-to-moderate example where waist minus neck drives most of the estimate.

Female example

65 in height, 13 in neck, 29 in waist, 39 in hip

The female equation adds waist and hip, subtracts neck, then adjusts by height.

Tracking example

Same height, smaller waist over time

When measuring conditions stay consistent, the tool can help track directional changes.

When to Use This Calculator

Use the Navy body fat calculator when you want a tape-based estimate that complements BMI, photos, and other body-composition checks.

Compare against BMI

BMI uses only height and weight. The Navy method adds circumference, so it can give more context for muscular or differently shaped bodies.

Track fitness progress

Repeated measurements under similar conditions can show whether waist, neck, and hip changes are moving in the expected direction.

Prepare for a tape test

The calculator helps you understand the inputs behind a tape estimate before reading the official rules for your situation.

How to Interpret the Navy Tape Result

Use the number as a repeatable estimate, not a diagnosis or an official military determination.

One result

A single result is a snapshot that can be affected by tape placement, hydration, posture, and rounding.

Repeated results

Two or three readings under the same conditions are more useful than one quick measurement.

Method comparison

Compare the result with BMI, waist trend, or a photo-based body fat estimate when you need more context.

Why the Number Can Change

The Navy circumference method is practical because it uses simple measurements, but the same person can see different estimates when the setup changes.

Tape angle

A tape that slopes up or down can add or remove circumference compared with a level measurement.

Breathing and posture

Holding breath, tightening the abdomen, or rounding shoulders changes waist and neck readings.

Rounding

Rounding height or circumference too early can affect the logarithm-based formula.

Navy Body Fat Calculator FAQ

AI Body Fat Calculator

Estimate body fat from a photo when you want a visual body-composition check.

Try photo estimate

BMI Calculator

Calculate BMI from height and weight, then compare it with circumference-based body fat.

Calculate BMI

Body Fat Estimate Pictures

Learn how visual estimates differ from tape measurements and BMI.

Read the guide

Body Recomposition Calculator

Plan calories, protein, and target body fat for a recomp phase.

Plan recomp