Body Fat Estimate Calculator

U.S. Navy circumference method

Enter each measurement in metric or imperial units. Fields stay in sync. Hip is required for female estimates and ignored for male estimates.

Sex

Height (cm)

Height (in)

Whole feet and inches —

Neck (cm)

Neck (in)

Waist (cm)

Waist (in)

Hip (cm)

Hip (in)

Estimated body fat —

General category —

U.S. Navy equations use circumferences and base-10 logarithms. Inputs can be cm or inches; units are auto-converted and results are equivalent.

Body-fat categories vary by source and age. Use this as a rough estimate, not a clinical diagnosis.

How tape-measure body-fat estimates work

Circumference formulas, not DEXA

This calculator estimates body-fat percentage from tape measurements using methods such as the U.S. Navy circumference equations. Results are screening estimates for general interest. Laboratory methods (DEXA, hydrostatic weighing) and quality callipers will disagree — sometimes by several percentage points.

Worked example

Two people with the same weight and height can return different Navy-method estimates if waist and neck differ. That is the point of circumference methods: they try to capture distribution, imperfectly.

Common mistakes

Measuring over thick clothing.
Pulling the tape tight enough to dent soft tissue.
Treating a single reading as a medical diagnosis.

FAQs

How does this relate to BMI?: BMI ignores fat vs muscle; this estimate tries (crudely) to infer fatness. See BMI & BRI.
Guide?: Body-fat estimates explained.

When this page helps

Use it when you want a transparent, browser-side calculation with the assumptions spelled out — then verify anything high-stakes against primary docs, a professional, or your own measurements. The related links below point to sibling tools and longer guides when you need more context.

Accuracy notes

Results depend entirely on the numbers you enter and the simplified model described above. Device clocks, tape measurements, market rates, and recipe conventions can all differ from a perfect textbook case. If an output looks surprising, re-check units first, then re-read the formula section.

Last updated: July 2026