UNDERSTAND THE METHOD
How to use this calculator
Use a flexible tape that does not stretch. Stand straight and relaxed. Men measure the neck and the abdomen at the navel. Women measure the neck, the narrowest natural waist and the widest part of the hips. Keep the tape level and snug without pressing into the skin, and measure each site two or three times. Enter height without shoes.
What the result can tell you
The Navy equations estimate body fat from circumferences and height. They do not measure fat directly, and a small change in tape position, posture or breathing can move the result. Military services each run their own measuring procedure, rounding and limits, so this result is not an official test. The ranges shown with an age are reference categories, not a diagnosis.
Navy body fat formula, where to measure and example results
The Navy circumference method needs only a tape measure. It uses height and two or three body circumferences, and it does not use weight or age. The equations work in inches, so the calculator converts centimeters to inches first.
| Who | Body fat % |
|---|---|
| Men | 86.010 × log10(abdomen − neck) − 70.041 × log10(height) + 36.76. Lengths in inches. |
| Women | 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. Lengths in inches. |
Where to place the tape
| Site | Who | Where |
|---|---|---|
| Neck | Men and women | Just below the larynx. Do not compress the skin. |
| Abdomen at navel | Men | Relax the abdomen. Keep the tape level with the navel. |
| Natural waist | Women | At the narrowest natural waist. Breathe out normally. |
| Hips | Women | Around the widest part of the buttocks. |
The next two tables show how the estimate moves with the waist measurement when height and the other sites stay the same. Each row is the calculator's own result for that example.
Example: man, 5 ft 10 in, neck 15 in
| Abdomen at navel | Estimated body fat |
|---|---|
| 30 in (76.2 cm) | 8.7% |
| 32 in (81.3 cm) | 13.4% |
| 34 in (86.4 cm) | 17.5% |
| 36 in (91.4 cm) | 21.3% |
| 38 in (96.5 cm) | 24.6% |
| 40 in (101.6 cm) | 27.8% |
| 42 in (106.7 cm) | 30.6% |
| 44 in (111.8 cm) | 33.3% |
Example: woman, 5 ft 5 in, neck 13 in, hips 38 in
| Natural waist | Estimated body fat |
|---|---|
| 26 in (66.0 cm) | 23.2% |
| 28 in (71.1 cm) | 25.9% |
| 30 in (76.2 cm) | 28.6% |
| 32 in (81.3 cm) | 31.1% |
| 34 in (86.4 cm) | 33.5% |
| 36 in (91.4 cm) | 35.9% |
| 38 in (96.5 cm) | 38.2% |
In these examples, each extra inch of waist adds about 1.1 to 2.3 percentage points, so careful, repeated measuring matters more than the decimal place.
The Navy's own 2026 assessment does not use these equations. Since 2026, Department of War Instruction 1308.03 checks waist-to-height first: a ratio below 0.55 meets the upper limit, and a body fat calculation follows at 0.55 or above, or above a lower limit a service sets. Each service chooses its own body fat step, and as of October 2026 they differ. The service rules were issued before the instruction and may change to match it.
Military body fat step after waist-to-height, October 2026
| Service and rule | Body fat step and limits |
|---|---|
| Navy (Guide 4, June 2026) | Read from the Navy's tables by weight (nearest pound) and height minus navel waist. No neck measurement. Limits 26% men, 36% women. |
| Air Force (AFMAN 36-2905) | Only if the fitness assessment is also not met. An InBody scale, or if none, tape tables by height and abdomen minus neck (men) or waist plus buttocks minus neck (women). Below 26% men, below 36% women. |
| Space Force (SPFMAN 36-2905, April 2026 change) | A lab test such as DXA, or if none, the same tape sites as the Air Force read from the Space Force table. 26.0% or below men, 36.0% or below women. |
| Marine Corps (MARADMIN 066/26) | Multi-site tape test or bioelectrical impedance; a Marine must meet the standard by at least one. Existing Marine Corps limits apply, with 1% more at 250 or more on both fitness tests and up to 26% men and 36% women at 285 or more. |
| Army (Directive 2026-13) | None. Waist-to-height is the only standard, and the tape test is rescinded. |
This calculator uses the same tape sites as the Air Force and Space Force tape tables, but their manuals do not say the tables come from these equations, and the services round their own way. The Air Force, for example, rounds the neck up and the abdomen down to the quarter inch. A result here can differ from an official one, especially near a limit. For the waist-to-height step, use the military screen on the waist-to-height page.
Common questions
How do I measure for the Navy body fat calculator?
Use a tape that does not stretch. Men measure the neck just below the larynx and the abdomen level with the navel. Women measure the neck, the narrowest natural waist and the widest part of the hips. Measure each site two or three times and use a typical value.
Why do the Navy equations not use weight?
The Navy circumference equations use only height and tape measurements. Weight is optional here and only splits your weight into fat mass and fat-free mass after the estimate. The Navy's own 2026 assessment is different: its tables do use weight.
Is this the official military body fat test?
No. It uses the published Navy circumference equations, but each military service runs its own measuring procedure, rounding, tables and limits. As of October 2026, the Navy reads body fat from a table of weight and height minus waist (Navy Guide 4, June 2026); the Air Force uses an InBody scale or, without one, neck-based tape tables (AFMAN 36-2905); the Space Force uses a lab test such as DXA or the same tape sites (SPFMAN 36-2905); the Marine Corps uses a multi-site tape test or bioelectrical impedance (MARADMIN 066/26); and the Army has no body fat step (Army Directive 2026-13). Follow your service's current instruction for an official assessment.
Does the Navy still use the neck in its body fat test?
No. Navy Guide 4 (June 2026) first checks waist-to-height: height rounded up and the navel waist rounded down to the half inch, with 0.5499 or below passing. At 0.5500 or above, Step 2 subtracts the waist from the height and reads body fat from the Navy's table by that difference and weight to the nearest pound. The limits are 26% for men and 36% for women. This calculator uses the older neck equations, so it cannot reproduce the Navy's table.
How is this different from the body fat calculator?
This page uses the Navy tape method only. The body fat calculator offers the same Navy option next to CUN-BAE, skinfold methods and a known result, so you can compare methods.
Sources & limitations11 sources
Sources checked September 12, 2026. These notes identify methods and assumptions. They have not received an independent clinical review.
- Department of Defense circumference equations.apps.dtic.mil
- The Navy circumference formulas for men and women, as used in a 2019 comparison study.pmc.ncbi.nlm.nih.gov
- Gallagher proposed body-fat ranges linked to BMI reference limits.pubmed.ncbi.nlm.nih.gov
- ACE body-fat fitness categories.acefitness.org
- ACSM fitness assessment manual; adapted age-specific categories.acsm.org
- Navy Guide 4 (June 2026): Step 2 reads body fat from tables by weight and height minus waist; limits 26% men, 36% women.mynavyhr.navy.mil
- AFMAN 36-2905 (March 24, 2026): body fat by InBody scale, or if none by tape tables by height and neck, abdomen, waist and buttocks; limits below 26% men, 36% women.static.e-publishing.af.mil
- SPFMAN 36-2905: Space Force body fat by a lab-grade test such as DXA, or if none by the same tape sites and its scoring table; 26.0% men, 36.0% women.static.e-publishing.af.mil
- MARADMIN 066/26: Marine Corps body fat by multi-site tape test or bioelectrical impedance; up to 26% men and 36% women at 285 or more on the PFT and CFT.marines.mil
- Army ABCP FAQ (effective July 7, 2026): the tape test and other body fat methods are rescinded.army.mil
- Army Directive 2026-13: waist-to-height is the sole ABCP standard; no tape test or other body fat method may challenge it.home.army.mil