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Health & FitnessGenerated accuracy model review: 2026-05-06

Body Fat % (Navy) accuracy and testing

This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.

Formula source

  • The U.S. Navy method relies on the principle that body fat distribution patterns differ between sexes. It uses logarithmic equations comparing the torso circumference (Waist/Hips) to the Neck and Height to estimate total body fat.

Test cases

Default input regression check

Generated from the checked-in default inputs and calculate function.

Inputs

  • Gender: Male
  • Height (ft): 5
  • Height (in): 10
  • Neck (in): 15
  • Waist (in): 34
  • Hip (in): 38

Expected outputs

  • Body Fat: 17.50%
  • Fat Mass: 0 lbs
  • Lean Mass: 0 lbs

Known limitations

  • Less accurate for individuals with extremely low body fat or unique body shapes (e.g. very thick necks from powerlifting).

Assumptions

  • The estimate uses the U.S. Navy circumference formula rather than direct body-fat testing.
  • Measurements must be taken consistently at the correct body landmarks for useful comparisons.
  • The method is best used for trend tracking and screening, not for precision body-composition analysis.

Unit handling

  • Gender accepts one of the configured options.
  • Height (ft) accepts numeric values.
  • Height (in) accepts numeric values.
  • Neck (in) accepts numeric values.
  • Waist (in) accepts numeric values.
  • Hip (in) accepts numeric values.
  • Body Fat is displayed as a percentage.
  • Fat Mass is displayed in lbs.
  • Lean Mass is displayed in lbs.

Rounding rules

  • Number displays use up to 2 decimal places in the calculator UI.
  • Percent outputs are displayed with two decimal places.

Version history

1.0.0 - 2026-05-06

Generated accuracy and testing page from the current navy-body-fat-calculator calculator definition.

Change log

2026-05-06

Published default regression test documentation and metadata fallbacks for Body Fat % (Navy).

Calculator transparency

Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.

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