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Body Fat Calculator

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This estimates body fat percentage using the US Navy method — a tape-measurement formula that's reasonably accurate for most people without needing special equipment like calipers or a DEXA scan.

Body Fat Calculator

Live
Estimated body fat
17.5%
Measure the neck just below the larynx, and the waist at the navel.

The US Navy formula

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

All measurements in inches.

Example

A man at 5'10" (70 in), 15 in neck, 34 in waist: %BF = 86.010×log₁₀(19) − 70.041×log₁₀(70) + 36.76 ≈ 17.5%.

Step-by-step guide

  1. Select your sex and enter your height.
  2. Measure your neck just below the larynx (Adam's apple).
  3. Measure your waist at the navel, and — for women — your hips at their widest point.
  4. Read your estimated body fat percentage.

Common mistakes

Pulling the tape measure too tight, or measuring over bulky clothing — both distort the circumference readings this formula depends on.
Expecting lab-grade precision — tape-measurement methods are a convenient estimate, generally within a few percentage points of more precise methods like DEXA scans, not an exact clinical measurement.

Frequently asked questions

How accurate is the Navy method?

It's considered reasonably accurate for most people, typically within a few percentage points of more precise methods like DEXA scans or hydrostatic weighing, which makes it a practical option without special equipment.

Why does the formula differ for men and women?

Typical fat distribution patterns differ between men and women, which is why the formula uses hip measurement for women but not for men, along with different constants.

What's a healthy body fat percentage?

Healthy ranges vary by age, sex, and individual factors, and there's no single number that applies to everyone. A doctor can help interpret your result in the context of your overall health.

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