military_tech

Army Body Fat Calculator | US Army Circumference Method

An Army body fat calculator estimates body-fat percentage with the US Army circumference method from AR 600-9: log-transformed height, neck, waist (and hip for women) measurements. It outputs estimated body fat % and pass/fail against the Army's age- and sex-specific screening thresholds.

Last updated: September 2026 · Free · No sign-up required

Results

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Quick reference

Classic AR 600-9 max body fat (screening weight failure):

Age	Men	Women
17–20	20%	30%
21–27	22%	32%
28–39	24%	34%
40+	26%	36%

straighten Tape protocol

Three measurements each site, averaged: neck below the larynx, abdomen at the navel (men), natural waist and widest hip (women).

rule Log formula

The equation is log-based, so one inch off the waist−neck difference moves the result more than you'd expect — measure carefully.

military_tech Category limits

Allowed body fat rises with age band and category (e.g., recruiters and warrant officers have their own tables).

science Accuracy limits

±3–4% versus DEXA; muscular soldiers can fail the tape while being lean — the Army permits alternate assessments.

lightbulb A real example — male soldier, 175 cm

Height 69 in, neck 15 in, waist 34 in.

Result: %BF = 86.010×log(19) − 70.041×log(69) + 36.76 ≈ 18.6% — passes the ≤22% standard for age 21–27.

What this means: The waist−neck difference drives everything: dropping the waist 2 inches (same neck) takes this soldier to about 15.4%.

Formula & methodology

Formula: Men: %BF = 86.010×log10(waist−neck) − 70.041×log10(height) + 36.76 (inches)

The US Army tape test

AR 600-9's circumference method estimates body fat from three or four tape measurements (inches), validated against hydrostatic weighing in the 1980s DoD study:

Men: neck (below larynx), abdomen (at navel); %BF = 86.010×log(waist−neck) − 70.041×log(height) + 36.76.
Women: neck, natural waist (narrowest), hip (widest); %BF = 163.205×log(waist+hip−neck) − 97.684×log(height) − 78.387.

Standards (screening, under-40 in the classic table): men ≤ 20% (some categories 22–26%), women ≤ 30% (32–34% by category and age). Measure at end of a normal exhale, tape level, snug not compressing; take three readings and average.

The method runs ±3–4% versus DEXA — it can misclassify very muscular soldiers, which is why the Army moved to additional assessments.

Authoritative source: U.S. Army H2F

Frequently asked questions

How does the Army calculate body fat with a tape?

Log formulas from AR 600-9: men use height, neck and waist; women add hip circumference. The measurements are in inches, plugged into published log equations validated against underwater weighing.

What is the max body fat percentage in the Army?

It depends on age, sex and category — classically 20% (men) and 30% (women) at 17–20, rising to 26% / 36% at 40+.

How accurate is the tape test?

Within about ±3–4% of DEXA for most people, but it systematically overestimates fat in heavily muscled soldiers.

Where exactly do I measure neck and waist?

Neck just below the Adam's apple with tape sloping slightly down at the back; men's waist at the navel, women's at the natural narrowest point, hips at the widest — all after a normal exhale.

What happens if I fail the tape test?

Failing the circumference screening typically triggers enrollment in the Army Body Composition Program: monthly weigh-ins, nutrition counseling, and a set timeframe to meet the standard. Continued failure can lead to a flag barring promotion, schools and awards, and eventually separation proceedings. The calculator's pass/fail line mirrors the screening standard — the program itself carries additional rules.

Why does the Army screen height and weight before taping?

The tape test is step two. Soldiers are first checked against the AR 600-9 height–weight table; only those exceeding the maximum allowable weight for their height get taped. If you are under the screening weight, body fat is never measured. Many soldiers who 'pass the tape' actually never take it — they clear step one.

Does the tape test penalize muscular soldiers?

It can. A thick neck — common in lifters — actually helps, because neck circumference is subtracted from the waist measurement. But very muscular soldiers with wide waists from heavy core training can still read high. This known bias is why the method gets revisited periodically; soldiers near the line should verify against the current regulation's procedures.

Are the standards different for men and women?

Yes — both the formula and the limits differ. Women are measured at neck, waist and hip with a separate equation, and their maximum allowable percentages run about 8–10 points higher than men's in each age bracket, reflecting essential body-fat differences. Age brackets also relax the standard: the 40+ limits sit several points higher than the 17–20 limits.

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