Body Fat Percentage Calculator
Estimate body fat using Navy circumference and BMI-based methods. See lean mass, fat mass, and ACE fitness classification.
Unit system
Body Fat % (Navy)
17.8%
AverageBody Fat % (BMI-based)
20.1%
Deurenberg formula estimate
Body Composition
Lean mass
61.7 kg
Fat mass
13.4 kg
Total weight
75 kg
ACE Classification (Male)
| Category | Range |
|---|---|
| Essential | 2–5% |
| Athletes | 6–13% |
| Fitness | 14–17% |
| Average | 18–24% |
| Obese | 25%+ |
Navy circumference method has a 3–4% error margin compared to DEXA scans. Results vary with measurement technique and individual body proportions. This is not medical advice.
How this tool works
The tool estimates body fat percentage using two independent methods. The Navy method uses circumference measurements: for men, BF% = 86.010 × 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 in inches). The Deurenberg BMI-based formula provides a secondary estimate: BF% = 1.20 × BMI + 0.23 × age − 16.2 (men) or − 5.4 (women). Lean mass equals total weight minus fat mass. The ACE fitness classification rates your result against population standards: Essential fat (2–5% men, 10–13% women), Athletes (6–13% / 14–20%), Fitness (14–17% / 21–24%), Average (18–24% / 25–31%), Obese (25%+ / 32%+).
Worked example
A 30-year-old man, 175 cm tall with a 37 cm neck and 85 cm waist, converts to 68.9 in height, 14.6 in neck, and 33.5 in waist. Navy BF% = 86.010 × log10(33.5 − 14.6) − 70.041 × log10(68.9) + 36.76 ≈ 19.2%. At 75 kg that gives 14.4 kg fat mass and 60.6 kg lean mass, placing him in the Average ACE category.
Frequently asked questions
How accurate is the Navy body fat method?
The Navy method has an error margin of 3–4 percentage points compared to DEXA scans. It is most accurate for people with average body proportions and tends to underestimate fat in very muscular individuals.
What is a healthy body fat percentage?
ACE defines fitness-range body fat as 14–17% for men and 21–24% for women. Athlete ranges are 6–13% (men) and 14–20% (women). Going below essential fat thresholds (2–5% men, 10–13% women) is medically dangerous.
What is lean mass?
Lean mass is everything in your body that is not fat: muscle, bone, water, and organs. It is calculated as total weight minus fat weight and is the key metric for strength training progress.