Estimate your body fat percentage using three scientifically validated methods — the U.S. Navy formula, the circumference method, and Jackson-Pollock 3-site skinfold measurements. Enter your measurements once, switch between methods to compare results, and see exactly where you fall on the body composition scale.
Pro tip: Take all circumference measurements on bare skin, standing relaxed, using a flexible tape pulled snug but not compressing the skin. For the most consistent results, measure first thing in the morning before eating.
Male 3-site: Chest (diagonal fold at the front of the armpit), Abdomen (vertical fold 1″ right of the navel), Thigh (vertical fold midway between hip and knee on the front of the thigh).
Fill in measurements for all three methods above to see how the estimates compare. A tighter spread indicates higher confidence in your result.
| Method | Body Fat % | Fat Mass | Lean Mass |
|---|---|---|---|
| Navy Method | — | — | — |
| Circumference | — | — | — |
| Skinfold | — | — | — |
How to Use the Body Fat Calculator
Start by selecting your preferred calculation method using the chip toggle at the top of the tool. The Navy Method requires only neck and waist measurements (plus hips for women), making it the fastest option. The Circumference Method adds forearm and wrist measurements for a slightly different equation. The Skinfold Method uses the Jackson-Pollock 3-site protocol and requires calipers. Choose your gender, enter your height and weight, fill in the required measurements, and your estimated body fat percentage, fat mass, lean mass, and FFMI update instantly. The coloured gauge shows where your result falls across five body composition categories so you can see at a glance whether you are in the essential, athlete, fitness, average, or obese range. Subscribers can enter a target body fat percentage to see exactly how much fat they need to lose and an estimated timeline based on a safe weekly deficit.
Body Fat vs BMI — Why Body Fat Matters More
Body Mass Index treats all mass equally, lumping muscle, bone, and fat together in a single ratio of weight to height. A lean, muscular athlete and a sedentary person of identical height and weight will produce the same BMI despite having radically different health risks. Body fat percentage cuts through that ambiguity by quantifying how much of your total mass is adipose tissue. Excess body fat — particularly visceral fat stored around internal organs — is directly correlated with insulin resistance, cardiovascular disease, and chronic inflammation. By tracking body fat instead of or alongside BMI, you get a far more meaningful indicator of metabolic health, training progress, and disease risk.
The Three Measurement Methods Explained
The U.S. Navy Method was developed by Hodgdon and Beckett at the Naval Health Research Center. For men it uses the formula BF% = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. For women it substitutes waist + hip − neck in the logarithm with adjusted coefficients. The method is accurate to about ±3–4% and requires only a tape measure. The Circumference Method extends the tape-based approach with additional measurement sites (forearm and wrist) and uses different regression coefficients from the YMCA methodology. The Skinfold (Jackson-Pollock) approach uses calipers to pinch subcutaneous fat at three sites — chest, abdomen, and thigh for men; triceps, suprailiac, and thigh for women — then converts the sum through a body density equation and the Siri formula (BF% = 495 / density − 450).
Understanding Essential Fat and Body Fat Categories
Essential fat is the minimum level required for normal physiological function — roughly 2–5% for men and 10–13% for women. Dropping below these thresholds disrupts hormone production, insulation of organs, and nutrient absorption. The Athletes range (6–13% for men, 14–20% for women) is typical of competitive athletes who maintain visible muscle definition. Fitness (14–17% for men, 21–24% for women) represents a fit, healthy body composition with moderate definition. Average (18–24% for men, 25–31% for women) is the range most adults fall into. Body fat above those thresholds — 25%+ for men and 32%+ for women — is classified as Obese and carries significantly elevated metabolic and cardiovascular risk.
What Is FFMI and Why Does It Matter?
Fat-Free Mass Index (FFMI) quantifies how much lean tissue you carry relative to your height, giving you a body composition metric that BMI cannot. The formula is lean mass in kilograms divided by height in metres squared, often with a normalising adjustment of +6.1 × (1.8 − height). An FFMI of 18–20 is typical for untrained men; 22–23 indicates a well-trained natural lifter; and values above 25 suggest either exceptional genetics or pharmacological assistance. For women, typical values are about 3–4 points lower. Tracking FFMI over time lets you verify that weight gained during a bulk is predominantly lean tissue rather than fat, and that weight lost during a cut is not coming disproportionately from muscle.
How to Measure Correctly for the Best Results
Neck: Measure just below the larynx (Adam’s apple) with the tape slightly sloping downward at the front. Waist: For the Navy method, measure at the navel level. Stand relaxed and breathe normally — do not suck in your stomach. Hips (women): Measure at the widest point of the buttocks with feet together. Skinfold sites: Pinch the skin and subcutaneous fat away from the muscle, place the caliper jaws 1 cm below your fingers, and read the measurement after 2 seconds. Take each measurement twice and average the results. All tape measurements should be taken on bare skin, pulled snug but not compressing tissue, and recorded to the nearest half inch or full centimetre. Measure at the same time of day under the same hydration conditions for the most consistent tracking over time.
Looking for related tools? Try our BMI Calculator to get a quick weight-to-height health snapshot, or explore all Health & Fitness tools.