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Body Fat Calculator (U.S. Navy Method)

Use this body fat calculator to estimate your body fat percentage using the U.S. Navy circumference method. Enter your gender, height, and a few simple body measurements to get an estimate of your body fat percentage and fitness category.

The formula differs for male and female calculations. Female calculations require an additional hip measurement.

Measure at the navel for men and at the narrowest point of the abdomen for women. Keep the tape snug but not compressing the skin.

Measure just below the larynx (Adam's apple) with the tape sloping slightly downward at the front.

Your total height in inches. For reference, 5 feet 10 inches equals 70 inches.

Required for female calculation. Measure at the widest point of the hips and buttocks. Not needed for males.

This calculator uses the U.S. Navy body fat estimation method, which relies on circumference measurements of the waist, neck, and hips. While not as precise as methods like DEXA scans or hydrostatic weighing, the Navy method provides a reasonable estimate using only a tape measure. It is widely used by the military and fitness professionals as a quick screening tool.

How It Works

U.S. Navy Body Fat Formula

Male: BF% = 86.010 x log10(Waist - Neck) - 70.041 x log10(Height) + 36.76; Female: BF% = 163.205 x log10(Waist + Hip - Neck) - 97.684 x log10(Height) - 78.387

For males, body fat percentage is calculated using the logarithm of the difference between waist and neck measurements, adjusted by height. For females, the hip measurement is added to the waist measurement before subtracting the neck, with different coefficients.

The U.S. Navy method uses circumference measurements as proxies for body fat distribution.

A larger waist relative to neck and height indicates higher body fat.

For females, the hip measurement is included because women tend to store more fat in the hip and thigh area.

The logarithmic formula was derived from correlation with hydrostatic weighing data.

All measurements must be in inches for the formula coefficients to produce accurate results.

Important Notes:

  • •The U.S. Navy method is an estimation and is less accurate than clinical methods like DEXA scans, hydrostatic weighing, or air displacement plethysmography.
  • •Accuracy can vary for individuals with unusual body proportions, very high muscle mass, or very low body fat.
  • •The formula was developed and validated primarily on military populations and may be less accurate for other demographics.
  • •Consistent measurement technique is important for tracking changes over time. Measure at the same time of day under the same conditions.

Worked Example

A male with a 34-inch waist, 15-inch neck, and height of 70 inches wants to estimate his body fat percentage.

Inputs:

  • gender:true
  • waist:34
  • neck:15
  • height:70
  • hip:0

Result:

Using the U.S. Navy method, the estimated body fat percentage is approximately 17.7%. This falls in the Fitness category for males. The lean mass percentage is approximately 82.3%.

Who Is This Calculator For?

  • fitness enthusiasts
  • people tracking body composition
  • military personnel
  • anyone curious about body fat levels

Frequently Asked Questions

The U.S. Navy method typically estimates body fat within 3 to 4 percentage points of clinical methods like hydrostatic weighing. Accuracy depends on consistent measurement technique. It works best as a tracking tool to monitor changes over time rather than as an absolute measurement.
For males, measure at the navel. For females, measure at the narrowest point of the abdomen, typically just above the navel. Stand relaxed, do not suck in your stomach, and keep the tape horizontal and snug without compressing the skin.
Women typically store more body fat in the hip and thigh area due to hormonal differences. The hip measurement improves the accuracy of the estimate for female body fat distribution patterns. The male formula accounts for fat distribution using only waist, neck, and height.
For men, 10-20% body fat is generally considered healthy. For women, 18-28% is considered healthy. Essential fat minimums are about 2-5% for men and 10-13% for women. Athletes often maintain lower levels within the healthy range.
Yes. People with significant muscle mass may get a somewhat higher body fat estimate because a muscular neck and larger frame can affect the circumference ratios. If you are very muscular, clinical methods like DEXA will give a more accurate result.
If you are tracking progress, measure every 2 to 4 weeks using the same technique and conditions. Daily measurements will show too much variability from hydration, food intake, and measurement error. Focus on the trend over weeks and months rather than any single reading.

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Last updated: April 11, 2026