Navy Body Fat Calculator

The Official U.S. Navy Body Fat Formula

The U.S. Navy body fat formula (also called the circumference or tape-measure method) was developed by Hodgdon and Beckett at the Naval Health Research Center in 1984. It is the formula used in the Navy's Physical Readiness Program (OPNAVINST 6110.1J). Two formulas apply — one for men, one for women — both based on log-transformed tape measurements.

The calculator above uses the mathematically equivalent density-based form (495 ÷ density − 450) with Hodgdon–Beckett's circumference density equations — you get the same result.

Navy PRT Body Fat Standards (Max Allowed %)

Per OPNAVINST 6110.1J, Navy personnel must stay at or below these body fat percentages to pass the Physical Readiness Test. Limits increase slightly with age.

Standards shown are simplified; the Navy PRP instruction defines additional sub-standards and appeals processes. This calculator is for reference only, not official assessment.

Navy Tape-Measure Method: How to Measure

1. Neck: Measure around the neck just below the Adam's apple / larynx. Keep the tape horizontal and look straight ahead. Record to the nearest half-inch, rounding up.
2. Waist (men): Measure horizontally at the navel. Stand relaxed, exhale normally — don't suck in. Round down to the nearest half-inch.
3. Waist (women): Measure at the narrowest point of the torso, usually above the navel. Round down to the nearest half-inch.
4. Hips (women only): Measure horizontally at the widest point of the buttocks. Round down to the nearest half-inch.
5. Height: Measure standing barefoot against a wall. Round down to the nearest half-inch.

Consistency matters more than precision: measure at the same time of day (morning is typical), in the same clothing, with the tape snug but not compressing skin.