# Body Fat Percentage Calculator

> Estimate body fat percentage with the U.S. Navy tape-measure method.

Page: https://freecalculator.tech/tools/body-fat-calculator

## How do I estimate body fat percentage with a tape measure?

The U.S. Navy tape method estimates body fat from height plus neck and waist measurements, with hip measurement included for the female formula.

## Formula

The U.S. Navy tape method estimates body fat from logarithms of height and body circumferences. Men use waist − neck; women use waist + hip − neck.

- Men: body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76, using inches.
- Women: body fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387, using inches.
- Metric measurements are converted to inches before the formula runs. Waist − neck, or waist + hip − neck, must be greater than zero because the formula uses logarithms.
- The U.S. Navy tape method estimates body fat from logarithms of height and body circumferences. Men use waist − neck; women use waist + hip − neck.
- Inputs used: Units, Sex used by the formula, Height, Neck circumference, Waist circumference, Hip circumference, Height (feet), Height (inches), and other shown inputs.
- Edge handling: Height must be greater than zero.; Neck circumference must be greater than zero.; Waist circumference must be greater than zero.; Hip circumference must be greater than zero.; Height (feet) cannot be negative..

## Inputs

- Units
- Sex used by the formula
- Height
- Neck circumference
- Waist circumference
- Hip circumference
- Height (feet)
- Height (inches)
- Neck circumference
- Waist circumference
- Hip circumference

## Worked example: Male example: 70 in tall, 34 in waist, 15 in neck

The Navy method estimates about 19.1% body fat for these tape measurements.
1. Use the male formula: 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76.
2. Compute the circumference term: 34 − 15 = 19 inches.
3. Plug in the values: 86.010 × log10(19) − 70.041 × log10(70) + 36.76.
4. The result is about 19.1% after rounding to one decimal place.

## Common questions

### How do I estimate body fat percentage with a tape measure?

The U.S. Navy tape method estimates body fat from height plus neck and waist measurements, with hip measurement included for the female formula.

### Where should I measure my waist, neck, and hips?

Use consistent tape-measure locations and keep the tape level without compressing the skin. Small measurement differences can change the estimate, so repeat each measurement and use the same method each time.

### Why does the calculator use inches even in metric mode?

The Navy equations are written with inch-based constants. Metric entries are converted to inches first so the same published formula can be applied consistently.

### Is the Navy method the same as a scan?

No. Tape formulas are practical estimates and can differ from DEXA, Bod Pod, hydrostatic weighing, or clinician measurements. Use the result as a rough tracking aid, not a diagnosis.

### How do I use the Body Fat Percentage Calculator?

Enter the required values for Units, Sex used by the formula, Height, Neck circumference, Waist circumference, and the other fields shown. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.

### What formula does the Body Fat Percentage Calculator use?

The U.S. Navy tape method estimates body fat from logarithms of height and body circumferences. Men use waist − neck; women use waist + hip − neck. The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.

## Limitations and assumptions

- The formula is sensitive to tape placement, posture, hydration, and rounding of measurements.
- It is not designed for children, pregnancy, bodybuilders, or clinical diagnosis.
- Results outside 2% to 75% are treated as likely input or unit errors rather than displayed as a valid estimate.
- Estimate for informational purposes only; not medical advice, diagnosis or treatment.
- Inputs outside the supported range are rejected rather than forced into a result.

## Cite this page

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