Body Fat Calculator
Estimate your body fat percentage from a few tape measurements. The headline figure uses the U.S. Navy method (developed at the Naval Health Research Center); the calculator also reports the BMI method estimate for comparison, your fat mass and lean mass, and — for ages 20 to 55 — how much fat stands between you and the Jackson & Pollock ideal for your age. Measure to the nearest ¼ inch (0.5 cm) for the best results.
Body Fat:
Advertisement — In-Article
(Responsive Fluid)
Reference tables
American Council on Exercise categories
| Description | Women | Men |
|---|---|---|
| Essential fat | 10-13% | 2-5% |
| Athletes | 14-20% | 6-13% |
| Fitness | 21-24% | 14-17% |
| Average | 25-31% | 18-24% |
| Obese | 32+% | 25+% |
Jackson & Pollock ideal body fat percentages
| Age | Women | Men |
|---|---|---|
| 20 | 17.7% | 8.5% |
| 25 | 18.4% | 10.5% |
| 30 | 19.3% | 12.7% |
| 35 | 21.5% | 13.7% |
| 40 | 22.2% | 15.3% |
| 45 | 22.9% | 16.4% |
| 50 | 25.2% | 18.9% |
| 55 | 26.3% | 20.9% |
Body fat, overweight, and obesity
Body fat — adipose tissue, in the scientific term — is not dead weight. It stores the lipids your body turns into energy, secretes hormones, cushions organs, and insulates you. It comes in two kinds. Essential fat is the floor your body needs to stay alive and keep reproductive function working: roughly 2–5% in men and 10–13% in women, which is why healthy ranges sit higher for women (about 21–33%) than for men (about 8–19%). Chasing a percentage at or below the essential floor is a conversation to have with a doctor, not a calculator. Storage fat is everything above that — subcutaneous fat under the skin and visceral fat packed around the organs inside the abdomen. It is the visceral kind that does most of the damage.
Excess storage fat is the road to overweight and then obesity — a condition the WHO counts among the leading preventable causes of death, linked to cardiovascular disease, stroke, type 2 diabetes, certain cancers, sleep apnea, and shorter life expectancy. Visceral fat is metabolically active in the worst way: it disturbs hormone balance, nudges LDL ("bad") cholesterol up and HDL ("good") cholesterol down, and promotes insulin resistance. Note the flip side, too: "overweight" on a scale does not automatically mean over-fat — muscle, bone, and water all weigh something, which is why heavily muscled people can be classified overweight while carrying little fat. That gap between weight and fat is the whole reason this calculator exists.
How the U.S. Navy method works
The equations come from work by Hodgdon and Beckett at the Naval Health Research Center (1984), fitted against hydrostatic weighing. Two versions exist — one in inches, one in centimeters:
Men
USC: BFP = 86.010·log10(waist − neck) − 70.041·log10(height) + 36.76
Metric: BFP = 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450
Women
USC: BFP = 163.205·log10(waist + hip − neck) − 97.684·log10(height) − 78.387
Metric: BFP = 495 / (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450
From the percentage, the masses follow directly: Fat Mass = BF × Weight and Lean Mass = Weight − Fat Mass. Treat the result as a solid estimate, not a lab value — the equations are averages fitted across many bodies. For clinical precision, bioelectric impedance or hydrostatic density testing is the next step up.
The BMI method
The second estimate needs nothing but height, weight, and age. It first computes your BMI, then applies the Deurenberg equations:
Adult men: BFP = 1.20 × BMI + 0.23 × Age − 16.2
Adult women: BFP = 1.20 × BMI + 0.23 × Age − 5.4
Boys: BFP = 1.51 × BMI − 0.70 × Age − 2.2
Girls: BFP = 1.51 × BMI − 0.70 × Age + 1.4
Because it never looks at your shape, the BMI method inherits every BMI limitation — it overstates fat on the muscular and understates it on the lightly built. The Navy figure is the one to act on; the BMI figure is a sanity check.
FAQ
How accurate is the U.S. Navy method?
Within a few percentage points of hydrostatic weighing for most people — if the tape work is careful. Measure snug, not tight, and at the right landmarks (see the sidebar). Sloppy measurements are the main source of error.
What is a healthy body fat percentage?
The ACE "Fitness" band is 14–17% for men and 21–24% for women, with "Average" running to 24% and 31%. Jackson & Pollock's ideals rise with age — see the table above. This calculator shows the ideal-based rows for ages 20–55.
Which should I trust, the Navy method or the BMI method?
The Navy method — it responds to where fat actually sits on your body. The BMI method is blind to the difference between muscle and fat.
Why do women need a hip measurement?
Women store proportionally more fat around the hips, so the women's Navy equation includes hip circumference. The men's equation needs only waist and neck.