Body Fat Percentage Calculator

US Navy Body Fat Formula

The US Navy circumference method (Hodgdon–Beckett equations) estimates body fat from a few tape measurements:

• 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

Circumferences are in inches. We also show a BMI-based estimate: %BF = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4 (sex = 1 for men, 0 for women).

Body Fat Categories (ACE)

Results are estimates and depend on accurate, consistent measurements. For clinical accuracy use a DEXA scan or hydrostatic weighing, and speak to your GP about any health concerns.

Frequently Asked Questions

How does the US Navy body fat method work?

It estimates body fat from tape-measure circumferences. For men it uses height, neck and waist; for women it adds the hip. Measure at the navel for the waist, below the larynx for the neck, and at the widest point for the hips.

What is a healthy body fat percentage?

Using the commonly cited ACE ranges, the fitness range is about 14–17% for men and 21–24% for women, while 25%+ (men) or 32%+ (women) is considered obese. Athletes are typically lower.

Is the US Navy method accurate?

It is usually within about 3–4% of more precise methods such as a DEXA scan or hydrostatic weighing, provided you measure carefully. Inconsistent tape placement is the biggest source of error.

What is the difference between the Navy and BMI methods?

The Navy method uses body circumferences and reflects where you carry fat. The BMI method (Deurenberg) uses only BMI, age and sex, so it cannot tell muscle from fat. We show both for comparison.

Why does the waist measurement matter so much?

In the Navy formula, body fat rises with the gap between waist and neck. A larger waist relative to the neck (and hip for women) means a higher estimated body fat percentage.