How accurate is the US Navy body fat method?

Studies generally put it within about 3-4 percentage points of DXA when measurements are taken carefully. Its strength is consistency over time rather than absolute precision.

Where exactly do I measure?

Neck just below the larynx with the tape sloping slightly downward at the front, waist at the navel for men and at the narrowest point for women, and hips at the widest point.

What is a healthy body fat percentage?

The American Council on Exercise lists roughly 14-24% as fitness to average for men and 21-32% for women. Essential fat is about 2-5% for men and 10-13% for women.

Why do my scales give a different number?

Bioelectrical impedance scales estimate body fat from body water, so hydration, food and time of day move the reading. The two methods are not interchangeable.

Body Fat Calculator

Estimate body fat percentage from tape measurements using the US Navy method.

Enter your details and your result will appear here.

What Is Body Fat?

This calculator estimates body fat percentage from tape measurements using the US Navy circumference method, then splits your weight into fat mass and lean mass. It works in inches or centimetres.

Understanding Your Body Fat Result

Circumference methods work because fat distribution follows predictable patterns: for men, most of the variance is captured by the difference between waist and neck; for women, hip circumference is added. The method was developed by the Naval Health Research Center for body composition standards and is popular because it needs nothing more than a tape measure.

How Is Body Fat Calculated?

Male: 495 / (1.0324 - 0.19077 log10(waist - neck) + 0.15456 log10(height)) - 450

Methodology

For men, body fat percentage is 495 divided by (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) minus 450, with all measurements in centimetres. For women, the denominator is 1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height). The Deurenberg BMI-based estimate (1.20 x BMI + 0.23 x age - 10.8 x sex - 5.4) is shown alongside for comparison.

Worked Example

A man who is 5 ft 10 in (178 cm) with a 15.5 in (39.4 cm) neck and a 34 in (86.4 cm) waist gets an estimate of about 15% body fat. At 180 lb that is roughly 27 lb of fat mass and 153 lb of lean mass.

Important Limitations

Accuracy depends heavily on consistent tape placement; a half-inch difference at the waist can shift the result by more than a percentage point. Compared with DXA, the Navy method typically falls within 3-4 percentage points, and it is less reliable at very low and very high body fat. It cannot detect where fat is stored internally. Use it to track change over time rather than as an absolute value.

Frequently Asked Questions

How accurate is the US Navy body fat method?: Studies generally put it within about 3-4 percentage points of DXA when measurements are taken carefully. Its strength is consistency over time rather than absolute precision.
Where exactly do I measure?: Neck just below the larynx with the tape sloping slightly downward at the front, waist at the navel for men and at the narrowest point for women, and hips at the widest point.
What is a healthy body fat percentage?: The American Council on Exercise lists roughly 14-24% as fitness to average for men and 21-32% for women. Essential fat is about 2-5% for men and 10-13% for women.
Why do my scales give a different number?: Bioelectrical impedance scales estimate body fat from body water, so hydration, food and time of day move the reading. The two methods are not interchangeable.