Body Fat Calculator: Estimate Your Body Fat Percentage

If you want to estimate your body fat percentage, the easiest way is to use our body fat calculator.

All you need is a tape measure. Enter your measurements in the boxes, then press the Calculate! button.

Body Fat Calculator

Estimate your body fat percentage with the US Navy tape-measure method.

Units Metric (cm) Imperial (in)

Sex Male Female

Height

Neck At the narrowest part, below the Adam’s apple.

Waist Men: at the navel. Women: at the narrowest part. Measure relaxed.

This is an estimate. It can be off by a few percentage points.

For best results:

Measure carefully and follow the instructions for each site.
Don’t pull the tape too tight.
Take each measurement two or three times and use the average.
Measure under similar conditions each time.

How Does the Body Fat Calculator Work?

This calculator is based on the US Navy body fat percentage estimation formulas, which are part of the US Department of Defense body composition standards.¹

They look like this:

Metric (measurements in cm)

Men: BF% = 495 / (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450
Women: BF% = 495 / (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450

Imperial (measurements 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

But instead of you having to do the math yourself, the calculator crunches the numbers for you.

How Accurate Is the Body Fat Calculator?

It’s more accurate than you might expect from such a simple method and just a tape measure.

In one study, with physically fit US Marines, the results were ~2.5 percentage points lower than DXA (a medical imaging and body composition reference method) in men and ~1–2.5 percentage points higher in women, depending on age.²

It only gives you an estimate of your actual body fat percentage, but that estimate can be surprisingly accurate.

However, it tends to overestimate body fat in very lean people and underestimate it in people with a lot of body fat.

In addition, it’s less accurate if you’re very muscular, have a neck that’s much thicker or thinner than average, or have an unusual body fat distribution.

But for the average person, it performs remarkably well, given how little equipment it requires.

Body Fat Percentage Ranges for Men and Women

These are common body fat percenage ranges, based on the American Council on Exercise (ACE) ranges.

Men

Body Fat Category	Body Fat %
Essential Fat	2–5%
Athletes	6–13%
Fitness	14–17%
Average	18–24%
Obese	25%+

Women

Body Fat Category	Body Fat %
Essential Fat	10–13%
Athletes	14–20%
Fitness	21–24%
Average	25–31%
Obese	32%+

These body-fat categories aren’t universally standardized, and the cutoffs can vary between organizations and measurement methods.

The Body Fat Calculator in the StrengthLog App

This body fat calculator is also available for free in our workout log app, StrengthLog.

When you use it in-app, you also get an estimate of your fat mass and fat-free mass in kilograms or pounds. That feature is not part of the actual US Navy body fat equation, which only requires a tape measure.³

Other Methods of Measuring Your Body Fat

There are many different ways to measure body fat, from equations like the US Navy one to smart scales to skin calipers and DXA (dual-energy X-ray absorptiometry) machines.

Some are more accurate than others (none of them are 100% exact), and some require expensive laboratory equipement.

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