Estimate your body fat percentage using the U.S. Navy tape-measure method — see your ACE body fat category, fat mass, lean mass, and age-adjusted Jackson & Pollock ideal ranges.
This Body Fat Calculator uses the U.S. Navy tape-measure method, which was validated for military fitness assessment and is widely used in clinical and fitness settings as a practical alternative to DEXA scanning or hydrostatic weighing. For men, it uses neck, waist, and height measurements; for women, it adds a hip measurement to account for sex-specific fat distribution. The formula produces an estimated body fat percentage, which the calculator then maps against ACE body fat categories: essential fat, athlete, fitness, acceptable, and obese — with separate ranges for men and women. Results are educational estimates. Body fat measurement without lab equipment carries a margin of error of roughly ±3–4%, so use this as a directional reading, not a clinical measurement. Always consult a healthcare provider for decisions based on body composition.
Measure your height, neck circumference, and waist circumference (at the navel) — and if you're female, your hip circumference at the widest point — then enter these alongside your sex and calculate. The result is an estimated body fat percentage and its corresponding ACE category. For men: essential fat is 2–5%, athlete 6–13%, fitness 14–17%, acceptable 18–24%, and obese ≥25%. For women: essential fat 10–13%, athlete 14–20%, fitness 21–24%, acceptable 25–31%, and obese ≥32%, per ACE guidelines. A result in the acceptable range isn't alarming, but it leaves meaningful room for improvement in health and performance. Athlete-range fat doesn't require athletic status — it just indicates a lean body composition.
The U.S. Navy body fat formula uses circumference measurements to estimate fat percentage:
Men: % body fat = 86.010 × log₁₀(abdomen − neck) − 70.041 × log₁₀(height) + 36.76
Women: % body fat = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
All measurements are in inches; height is in inches. The formula was developed for and validated by the U.S. Navy and is referenced in military fitness standards. It estimates body density via circumference as a proxy for the direct measures used in DEXA or hydrostatic weighing.
The ACE body fat chart provides the most widely cited US reference for body fat percentage categories. These ranges apply to both men and women and are used by fitness professionals nationwide.
| Description | Women | Men |
|---|---|---|
| Essential fat | 10-13% | 2-5% |
| Athletes | 14-20% | 6-13% |
| Fitness | 21-24% | 14-17% |
| Acceptable | 25-31% | 18-24% |
| Obese | 32+% | 25+% |
The Jackson & Pollock research provides age-adjusted ideal body fat ranges, recognizing that body composition norms shift across the lifespan. These values represent healthy targets by decade rather than a single universal standard.
| Age | Women | Men |
|---|---|---|
| 20 | 17.7% | 8.1% |
| 25 | 18.4% | 9.3% |
| 30 | 19.3% | 10.5% |
| 35 | 20.4% | 11.8% |
| 40 | 21.8% | 13.1% |
| 45 | 23.4% | 14.5% |
| 50 | 25.1% | 15.9% |
| 55 | 26.9% | 17.3% |
| 60+ | 28.7% | 18.8% |
The ACE body fat chart provides the most widely cited US reference. For men, fit/athlete range is 6–17%; for women, 14–24%. But age matters: body fat naturally increases with age even at a stable weight, because muscle mass declines (sarcopenia) and metabolic rate slows. A 25-year-old man and a 55-year-old man at the same body fat percentage are in different physiological positions. Research from the Journal of Obesity suggests that age-adjusted thresholds better predict metabolic health than universal cutoffs. In practice, a 50-year-old woman at 28% body fat is in a healthier position than a 30-year-old woman at 28% body fat who has never exercised — context always matters alongside the number.
Not all body fat carries the same health risk. Subcutaneous fat sits under the skin and is the "pinchable" fat on your thighs, arms, or hips. Visceral fat wraps around the abdominal organs and is metabolically active in a way subcutaneous fat isn't — it secretes inflammatory compounds that drive insulin resistance, elevated triglycerides, and cardiovascular risk. The NIH specifically flags abdominal fat as a stronger predictor of type 2 diabetes and heart disease than total body fat percentage. A body fat calculator estimates total fat; it doesn't directly measure visceral fat. But waist circumference — already gathered for this calculation — is a reasonable proxy: men above 40 inches and women above 35 inches carry more visceral fat risk. Someone with a moderate total body fat percentage but a high waist circumference likely carries more dangerous fat than the percentage alone suggests.
The scientific term for body fat is adipose tissue. Adipose tissue serves a number of important functions. Its primary purpose is to store lipids from which the body creates energy. In addition, it secretes a number of important hormones, and provides the body with some cushioning as well as insulation.
Body fat includes essential body fat and storage body fat. Essential body fat is a base level of fat found in most parts of the body, necessary for maintaining life and reproductive functions. The amount of essential fat differs between men (2-5%) and women (10-13%). The healthy range of body fat is typically 8-19% for men and 21-33% for women.
Storage fat is fat that accumulates in adipose tissue, either as subcutaneous fat (deep under the dermis and wrapped around vital organs) or visceral fat (located inside the abdominal cavity, between organs). While some storage fat is ideal, excess amounts can have serious negative health implications.
The honest answer: reasonably useful, but not precision medicine. The Navy tape method has a margin of error of approximately ±3–4 percentage points compared to DEXA scanning, which is considered the gold standard for body composition measurement. Other field methods — bioelectrical impedance (BIA) scales and handheld devices — are similarly imprecise and are affected by hydration, meal timing, and electrode placement. Skinfold caliper tests, when done by a trained practitioner using a validated protocol like the Jackson-Pollock 3-site or 7-site method, reduce error to ±2–3%. DEXA (dual-energy X-ray absorptiometry) and hydrostatic (underwater) weighing are the most accurate but require clinical access. For most people tracking progress over time, the tape method is sufficient — what matters most is consistent methodology and repeated measurements, not absolute precision.
Developed at the Naval Health Research Center by Hodgdon and Beckett. This is the primary method used by our calculator.
For males: Measure waist at navel level and neck below the larynx.
For females: Measure waist at smallest width, neck below larynx, and hips at largest point.
An alternative estimation using Body Mass Index and age for when circumference measurements aren't available.
Fat Mass Formula
FM = BF × Weight
Lean Mass Formula
LM = Weight - FM
Reducing body fat percentage requires a caloric deficit — taking in fewer calories than you burn — combined with resistance training to preserve or build lean mass. The CDC's guidance on healthy weight loss targets 1–2 pounds per week, achieved with a 500–1,000 kcal/day deficit. Because roughly 3,500 kcal ≈ 1 lb of fat, a 500 kcal/day deficit yields about 1 lb/week. Protein intake matters significantly during fat loss: the USDA AMDR sets protein at 10–35% of calories, but athletes and active adults aiming to preserve muscle often target 1.2–2.0 g/kg of bodyweight. Cardio reduces total fat; resistance training redirects composition toward lean mass even when total weight barely moves. Spot-reduction (targeting fat at a specific body part) isn't supported by evidence — fat loss is systemic.
Elite endurance athletes commonly train at 8–12% (men) and 15–20% (women) body fat. Elite male bodybuilders can go below 5% temporarily for competition, which is below essential fat levels and is not a sustainable or healthy long-term state. For recreational athletes and active adults, the ACE "fitness" range (14–17% men, 21–24% women) is an achievable and health-supporting target. Performance doesn't always benefit from the lowest possible body fat — research consistently shows that below a threshold, power-to-weight benefits plateau and injury risk rises. For most non-competing adults, the athlete and fitness ranges represent excellent outcomes, not mandatory standards.
The two biggest drivers of your body fat percentage are total fat mass and total lean mass. Age reduces lean mass even without weight change, which is why body fat typically creeps up over decades without any change in diet or activity. Sex is foundational: women require more essential fat (10–13%) than men (2–5%) for hormonal and reproductive health. Diet composition, caloric balance, and resistance training determine how body fat changes over time. Measurement timing matters: measure first thing in the morning, after using the bathroom and before eating or drinking, for consistency. Pregnancy, recent illness, major hormonal changes, and extreme hydration states can affect measurements significantly.
Derek is a software engineer, 5'11" (71 in), 185 lb, with a waist of 36 in and neck of 16 in. Plugging those into the Navy formula: log₁₀(36 − 16) = log₁₀(20) ≈ 1.301; log₁₀(71) ≈ 1.851. Body fat ≈ 86.010 × 1.301 − 70.041 × 1.851 + 36.76 ≈ 111.89 − 129.65 + 36.76 ≈ 19.0%. That puts Derek in the acceptable range for men but short of the fitness category. He trains twice a week but doesn't prioritize strength work — adding two resistance sessions could meaningfully shift his composition over 3–6 months.
Maria is a nurse, 5'4" (64 in), 145 lb, waist 31 in, hip 40 in, neck 13.5 in. Formula input: log₁₀(31 + 40 − 13.5) = log₁₀(57.5) ≈ 1.760; log₁₀(64) ≈ 1.806. Body fat ≈ 163.205 × 1.760 − 97.684 × 1.806 − 78.387 ≈ 287.24 − 176.44 − 78.39 ≈ 32.4%. That places Maria just into the obese range for women per ACE. Her BMI might be 24.9 — technically "healthy" — yet her body composition tells a different story, exactly the limitation that makes this calculator a valuable complement to BMI.
Take all measurements in the same spot, same time of day, and ideally the same day of the week to reduce variability.
Focus on percentage change over time, not the absolute number — a 2-point reduction over 12 weeks is a meaningful and trackable result.
Pair body fat tracking with lean body mass tracking; a reduction in fat with stable or rising lean mass is an ideal outcome, even if the scale barely moves.
Don't chase athlete-range percentages unless you're competing — the fitness and acceptable categories support excellent long-term health.
Resistance training is more effective than cardio alone for shifting composition — it builds lean mass while fat loss proceeds from a caloric deficit.
If your result seems inconsistent with how you look or feel, consider a professional assessment — a registered dietitian or certified trainer can conduct a caliper test or refer you to a DEXA scan.
For women, ACE guidelines classify 25–31% as acceptable and 21–24% as fitness range. Athlete range is 14–20%, and essential fat is 10–13%. The right target depends on your health goals and age.
For men, acceptable is 18–24%, fitness is 14–17%, and athlete is 6–13% per ACE. Essential fat floors at 2–5%. Most active men aim for the fitness category.
The Navy tape method is accurate within ±3–4% compared to DEXA scanning. It's useful for tracking trends over time but shouldn't be treated as a clinical-grade measurement.
For most men, abs become visible at around 10–12% body fat; for women, around 16–19%. Individual variation in fat distribution and muscle development affects this significantly.
Body fat percentage is more informative because it distinguishes fat from muscle, which BMI cannot. However, both are estimates — neither replaces a full clinical assessment.
Visceral fat surrounds abdominal organs and releases inflammatory compounds that raise the risk of type 2 diabetes, heart disease, and stroke, per the NIH. Waist circumference is the practical proxy for visceral fat at home.
Monthly is appropriate for most people tracking progress. More frequent measurement doesn't add accuracy and can create unnecessary anxiety around normal daily fluctuations.
Brief disclaimer: This calculator provides educational estimates using the U.S. Navy circumference method. Results carry a margin of error of approximately ±3–4% compared to clinical-grade measurements like DEXA scanning. Body fat percentage is one of many health indicators and should not be used in isolation for medical decisions. Consult a qualified healthcare provider for personalized body composition assessment and health recommendations.