Body Fat Calculator (US Navy Method)
Estimate body fat percentage with the US Navy circumference method from height, neck, waist and hips, plus fat mass, lean mass and the ACE category.
Results
Body fat categories (ACE)
| Category | % |
|---|---|
| Essential fat | 2–5 |
| Athletes | 6–13 |
| Fitness | 14–17 |
| Average | 18–24 |
| Obese | ≥ 25 |
- US Navy circumference method (Hodgdon & Beckett). Measure the neck below the larynx, the waist at the navel (men) or narrowest point (women), and the hips at the widest point. Typical error is ±3–4%.
What is Body Fat Calculator?
Estimates body fat percentage from a few tape measurements using the US Navy formula. With your weight it also shows fat mass and lean mass, and it places the result in the American Council on Exercise (ACE) categories.
How to use Body Fat Calculator
- Choose units and Sex.
- Enter Height, Neck and Waist (and Hips for women).
- Optionally enter Weight to get fat and lean mass.
Example
Male, height 180 cm, neck 38 cm, waist 85 cm
Body fat 16.2%, Fitness
When to use Body Fat Calculator
Use it to track changes over time with consistent measuring. Typical error is about ±3–4 percentage points compared with DEXA; it is less accurate for very lean or very muscular people.
How Body Fat Calculator works
The Hodgdon & Beckett (US Navy) equations, in inches: men %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76; women %BF = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. Centimetre input is converted to inches first. Fat mass = weight × %BF and lean mass = weight − fat mass. ACE categories: men essential 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25%+; women 10–13%, 14–20%, 21–24%, 25–31%, 32%+.
Common Use Cases
- Tracking body composition during a diet
- Estimating lean mass for Katch-McArdle BMR
- Checking a fitness test standard
- Comparing with BMI
FAQs
Where exactly should I measure?
Neck just below the larynx; waist at the navel for men and at the narrowest point for women; hips at the widest point. Keep the tape level and do not pull it tight.
Why do I need the hip measurement only for women?
The original Navy equations for men use only neck and waist; the women's equation includes the hips.
How accurate is it?
Within a few percentage points for most people, which is good enough to track trends.