ACE body fat categorization
| 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%+ |
Reference: American Council on Exercise (ACE). Ranges shown as used by this calculator (men Fitness 14–17%, women Fitness 21–24%, etc.).
Jackson & Pollock ideal body fat
| 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
Adipose tissue stores energy, secretes hormones, and provides cushioning and insulation. Essential fat supports life and reproduction (~2–5% in men, ~10–13% in women). Storage fat includes subcutaneous and visceral fat — some is healthy; excess raises risk.
Weight alone is not body fat: muscle, bone, and water also matter. Highly muscular people can be “overweight” on BMI without excess fat.
Potential complications of excess body fat
Excess fat — especially visceral fat — is linked to poorer quality of life, sleep apnea, cardiovascular disease, stroke, certain cancers, type 2 diabetes, disrupted hormones, higher LDL, lower HDL, and insulin resistance. Managing food and movement remains the primary lever for most people.
How this calculator measures body fat
U.S. Navy method (Hodgdon & Beckett, 1984): circumference equations using neck, waist, height (and hips for women). Results are estimates (~±3–4% vs clinical methods).
BMI method: adult estimate from BMI and age (Deurenberg-style). Useful as a second reference — less precise than tape when measurements are careful.
Fat mass = body-fat % × weight. Lean mass = weight − fat mass.
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Disclaimer: Educational estimate only — not a diagnosis. For clinical accuracy, use DEXA, hydrostatic weighing, or professional assessment. Discuss very low body-fat targets with a clinician.
