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Body Fat Calculator
Estimate body-fat % three ways — US Navy (Hodgdon-Beckett) circumference, the current Army 2023 one-site abdominal method (Directive 2023-11, sole-authorized 2024; the old neck+waist two-site test is deprecated), or BMI-Deurenberg — with category ranges by sex, a fat/lean mass split and FFMI scored against the ~25 natural ceiling. A fitness estimate (±3–4% vs DEXA); circumference methods approximate — use DEXA/calipers for precision. Accurate, instant and free — for United States.
What these mean:
What these mean:
What these mean:
What these mean:
By the US Navy (Hodgdon-Beckett) method, your body fat is ≈ 19.4% — fat mass ≈ 15.9 kg, lean mass ≈ 65.8 kg, FFMI ≈ 20.8. Category: Average. An estimate (±3–4% vs DEXA); circumference methods approximate — DEXA/calipers for precision. General fitness guidance.
Body fat
19.4%
Fat mass
15.9 kg
Lean mass
65.8 kg
FFMI
20.8
Category: Average
FFMI vs the ~25 natural ceiling
An estimate — general fitness guidance
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed July 2026. Figures follow the methods and sources set out in our editorial standards.
US Navy (Hodgdon-Beckett) / current Army 2023 one-site (Directive 2023-11) / BMI-Deurenberg methods. An estimate (±3–4% vs DEXA) — general fitness guidance.
Army ABCP 2023 (Directive 2023-11) · as of 2024
Take it further: check your BMI, set your daily fuel with the Macro Calculator, and track progress with the Weight-Loss Percentage Calculator.
Three ways to estimate body fat — Navy, Army 2023 & BMI
Body-fat % is estimated three ways: the US Navy (Hodgdon-Beckett) circumference method, the current Army 2023 one-site abdominal method (Directive 2023-11), and a BMI-based (Deurenberg) estimate. Each also reports fat mass, lean mass and FFMI. Every value carries its unit (% / kg).
US Navy (circumference)
tape: neck, waist (+ hip women)
men: 86.010·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76
Women use waist + hip − neck. Inches; the generic body-fat standard (NHRC).
Army 2023 one-site
abdomen + weight + sex
%BF = a + b·weight(lb) + c·abdomen(in)
The current ABCP method (Directive 2023-11). One abdominal measurement at the navel — no height, no neck.
- 1First log term: 86.010 × log₁₀(36 − 16) = 86.010 × log₁₀(20) = 111.90.
- 2Height term: 70.041 × log₁₀(70) = 129.24.
- 3Combine (+ 36.76): 111.90 − 129.24 + 36.76 = ≈ 19.4% body fat.
The current Army 2023 one-site test (the two-site is deprecated)
Army Directive 2023-11 replaced the old two-site tape test (neck and waist, plus hip for women) with a single one-site abdominal measurement at the navel, combined with weight and sex. It has been the sole authorized ABCP method since 2024. Most third-party “army body fat calculator” pages still show the deprecated two-site formula — this tool uses the current one-site standard.
Worked example · Army 2023, woman, 150 lb, abdomen 32″
Body-fat categories — by sex
The result is classified into ACE category ranges, which differ by sex. This tool applies the correct table automatically:
| Category | Men | Women |
|---|---|---|
| Essential | 2–5% | 10–13% |
| Athlete | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | ≥ 25% | ≥ 32% |
FFMI and the ~25 natural ceiling
FFMI (fat-free mass index) is lean mass (kg) ÷ height (m)², the muscularity metric that a body-fat number alone misses. The normalized FFMIadjusts it to a 5′11″ reference: FFMI + 6.1 × (1.8 − height_m). A normalized FFMI near ~25 sits around the natural (drug-free) ceiling.
Where does ~25 come from?
It’s an estimate — about ±3–4% vs DEXA
Circumference and BMI-based methods are estimates, not measurements. They typically run about ±3–4% versus a DEXA (DXA) scan, the practical reference standard, and the Navy method carries a small bias. For precision use DEXA or professionally administered calipers.
An estimate — general fitness guidance
Frequently asked questions
This tool offers three methods. The US Navy (Hodgdon-Beckett) method uses tape measurements: for men, %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76; for women it adds hip (waist + hip − neck). The current Army 2023 one-site method uses a single abdominal measurement plus weight and sex. The BMI-based Deurenberg method uses BMI, age and sex. All are circumference/BMI estimates — accurate to about ±3–4% versus a DEXA scan.
Army Directive 2023-11 replaced the old two-site tape test (neck and waist, plus hip for women) with a single one-site abdominal circumference method, measured at the navel, combined with body weight and sex. It became the sole authorized Army Body Composition Program (ABCP) method in 2024. Many third-party "army body fat calculator" pages still show the deprecated two-site formula — this tool uses the current one-site standard.
Circumference and BMI-based methods are estimates, not measurements. They typically run about ±3–4% versus a DEXA (DXA) scan, the practical reference standard, and the US Navy method carries a small bias (roughly −2.6% in men, +2.3% in women). For a precise figure use DEXA or professionally administered skinfold calipers. Treat this as general fitness guidance and a good ballpark, not a clinical result.
By the widely cited ACE ranges, essential fat is about 2–5% for men and 10–13% for women; athletes 6–13% (m) / 14–20% (f); fitness 14–17% (m) / 21–24% (f); average 18–24% (m) / 25–31% (f); and obese above roughly 25% (m) / 32% (f). Ranges differ by sex, so this tool applies the correct table automatically.
FFMI (fat-free mass index) is your lean mass in kg divided by height in metres squared — a muscularity metric that body-fat % alone does not capture. The normalized FFMI adjusts it to a 5’11″ reference (FFMI + 6.1 × (1.8 − height_m)). A normalized FFMI near ~25 sits around the natural, drug-free ceiling: in the well-known Kouri 1995 study, all 42 drug-free athletes scored at or below 25.
If you have a tape measure, the US Navy method is the most common general standard. If you are a soldier checking ABCP compliance, use the current Army 2023 one-site abdominal method. If you have no tape, the BMI-based Deurenberg method needs only height, weight, age and sex — but it is the least precise because it cannot see where your weight is muscle versus fat.
Method, formulas & references
Methodology: US Navy (Hodgdon-Beckett) circumference — men 86.010·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76, women add hip; current Army 2023 one-site (Directive 2023-11) — %BF = a + b·weight(lb) + c·abdomen(in); BMI-Deurenberg — 1.20·BMI + 0.23·age − 10.8·(1 male/0 female) − 5.4. Fat mass = weight × %BF; FFMI = lean(kg) ÷ height(m)². All calculations run client-side and nothing is stored. An estimate (±3–4% vs DEXA) — general fitness guidance, not medical advice.
Cross-links
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed July 2026. Figures follow the methods and sources set out in our editorial standards.
US Navy (Hodgdon-Beckett) / current Army 2023 one-site (Directive 2023-11) / BMI-Deurenberg methods, with category ranges and FFMI. An estimate (±3–4% vs DEXA) — circumference methods approximate; use DEXA or calipers for precision. General fitness guidance, not medical advice.
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