Male, 35 years, 178 cm (70 in), neck 38 cm (15 in), waist 89 cm (35 in)
BF% = 86.01 × log10(35 − 15) − 70.041 × log10(70) + 36.76 ≈ 19%. Below the 26% limit for age 35 - comfortable pass. Healthy fitness range.
Army Body Fat Calculator - Free Online Calculator
The U.S. Army uses a tape-test formula to estimate body fat percentage from a few simple body circumferences. Different from generic body-fat methods, it's the official AR 600-9 standard and includes age-based service limits.
- Formula shown on the page
- Runs in your browser
- Your inputs stay private
yr
cm
cm
Just below larynx
cm
At the navel
Army body fat
17.0%
Tape-test estimate
Army limit (M, age 25)
24%
Pass
Within Army standards
Your estimated body fat is 17.0% - at or below the AR 600-9 ceiling of 24% for your age band.
AR 600-9 max body fat by age
- Men: 22% (17-20), 24% (21-27), 26% (28-39), 28% (40+)
- Women: 30%, 32%, 34%, 36% across same age bands
Tape tests are estimates ±3-4% absolute. For high-precision body composition, consider DEXA or hydrostatic weighing. Always measure with a non-stretch tape, snug but not compressing skin, and average three readings per site.
Understanding the Army Body Fat Calculator
The U.S. Army body fat formula (AR 600-9 standard) is the official body composition test used by all U.S. military branches and many civilian fitness contexts where a no-equipment body fat estimate is needed. Unlike the related U.S. Navy method, the Army version uses age-banded service limits - a 35-year-old male needs to be below 26% body fat to pass, a 45-year-old below 28%. Beyond military use, this calculator is useful for anyone wanting a second body-fat estimate alongside other methods (BMI, body fat scales, calipers) for triangulation.
Body fat percentage is more meaningful than weight or BMI for assessing fitness. Two people of identical height and weight can have wildly different body compositions - one lean and athletic at 15% body fat, another sedentary at 30%. The Army formula gives you a number based on tape measurements at the neck, waist, and (for women) hips - accurate to ±3-4% of DEXA scans when measurements are taken carefully.
Using the Army Body Fat Calculator in 5 steps
Pick your gender - the formula and service limit differ by sex.
Enter age, height and neck circumference (just below the larynx).
Enter waist circumference at the navel (men) or the smallest point above the hip (women).
Women also enter hip circumference at the widest point.
Read your body fat % and the Army limit for your age.
How the Army Body Fat Calculator works
The formula uses the natural log relationship between body fat and the circumferences specified by AR 600-9. Inputs are converted to inches because the formula is empirically derived in U.S. units. Pass means BF% is at or below the age-band ceiling.
Formula
Men: BF% = 86.01·log10(waist − neck) − 70.041·log10(height) + 36.76 Women: BF% = 163.205·log10(waist + hip − neck) − 97.684·log10(height) − 78.387
- Inputs in inchesConvert from cm if needed
How the Army Body Fat Calculator gets its answer
AR 600-9 specifies logarithmic regressions derived from extensive military body composition data. For men: BF% = 86.01 × log10(waist − neck) − 70.041 × log10(height) + 36.76. For women: BF% = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. All measurements in inches. The logs reflect the non-linear relationship between circumferences and body fat - straight-line regressions don't fit the data as well as logarithmic models.
Army body fat limits by age and gender (must be at or below to pass): Men 17-20: 22%, 21-27: 24%, 28-39: 26%, 40+: 28%. Women 17-20: 30%, 21-27: 32%, 28-39: 34%, 40+: 36%. The limits acknowledge that body fat percentage rises naturally with age and provide more lenient thresholds for older service members.
Measurement technique is critical for accuracy. Use a flexible non-stretching tape. Measure on bare skin or thin shirt. Exhale normally - don't suck in or hold breath. Neck: just below the Adam's apple, tape level horizontally. Waist (men): at the navel, tape parallel to floor. Waist (women): at the narrowest point of natural waist. Hip (women): at the widest point of buttocks. Take three measurements at each site and average; this reduces error by 50% versus single measurements.
Worked examples
Female, 28 years, 165 cm (65 in), neck 32 cm (12.6 in), waist 76 cm (30 in), hip 100 cm (39.4 in)
BF% = 163.205 × log10(30 + 39.4 − 12.6) − 97.684 × log10(65) − 78.387 ≈ 28%. Below the 32% limit for age 28 - comfortable pass. Average-fitness body composition.
When to use the Army Body Fat Calculator
- U.S. military and aspiring recruits checking compliance with AR 600-9 standards.
- Civilians wanting a no-equipment body fat estimate as an alternative to scales or calipers.
- Fitness enthusiasts triangulating body fat from multiple methods for higher confidence.
- Annual fitness assessments where body composition is a tracked metric.
- Coaches teaching clients to take their own body measurements consistently over time.
Common mistakes and gotchas
- Measuring inconsistently across time. Same tape, same time of day, same fasted state matter.
- Sucking in stomach or wearing thick clothing. Both bias the result lower than reality.
- Confusing the Army formula with the Navy formula - different coefficients, can produce 1-3 percentage point differences.
- Treating the result as precise. ±3-4% absolute error is normal for tape-test methods.
- Ignoring waist trends. Even within passing range, rising waist indicates declining body composition.
Get more out of this tool
- Always take 3 measurements at each site and average. Reduces error meaningfully.
- Measure first thing in the morning, fasted, after bathroom. Consistency over time matters more than absolute accuracy on any single day.
- Use a soft fabric tape, not a metal carpenter's tape. Press snug but don't compress skin.
- Track over months, not weeks. Body composition changes slowly; weekly readings are noise.
- Pair this calculator with the body fat, BMI and lean body mass calculators on this site for complete body composition tracking.
Questions about the Army Body Fat Calculator
Is the Army formula accurate for civilians?
Reasonably - it's a tape-test estimate, ±3-4% absolute. For high-precision body fat, DEXA or hydrostatic weighing is needed.
What are the Army body fat limits?
Men: 22% (17-20 yrs), 24% (21-27), 26% (28-39), 28% (40+). Women: 30%, 32%, 34%, 36% across the same age bands.
Why does the formula use logarithms?
The relationship between body fat and circumferences isn't linear. Logs fit the empirical data better than a straight line.
How is this different from the Navy formula?
Different coefficients, derived from different population samples. Both produce similar BF% for most people but can differ by 1-3 percentage points.
What if I fail the standard?
The Army uses this for compliance, not as a fitness verdict. Pair it with diet adjustment, calorie tracking and resistance training to drop fat while preserving muscle.
Does the tape need to be tight or loose?
Snug but not compressing the skin. Take three measurements at each site and average - this reduces error from minor positioning differences.
Track health metrics with care
Body composition, daily energy needs and pregnancy timelines all rest on formulas validated across millions of people, but no single number tells the whole story. The values from this calculator are point estimates with a known margin of error - body fat from skinfold or US Navy method has roughly a ±3% standard error compared to a DEXA scan, and BMR can vary ±10% person to person at the same height and weight. Use these numbers to track trends week over week, not to chase decimal precision day to day.
Pair this tool with the BMR, TDEE, calorie and macro calculators to turn a single measurement into an actionable plan. None of these tools are a substitute for a qualified doctor, registered dietitian or certified strength coach - but they remove the busywork so you spend more time on training and recovery, less on math.
The Army Body Fat Calculator is part of the Health & Fitness suite on Online Calculator Tools, alongside 6 related calculators. All tools share the same UI patterns, the same privacy-first rendering (nothing is sent to a server), and the same commitment to showing the formula and assumptions behind every result.