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Body Fat Calculator

Estimate body fat from measurementsRuns locally · nothing uploaded

Body fat
17.9%
Category
Fitness
Fat mass
28.6 lb
Lean mass
131.4 lb

Estimates based on general formulas, for information only. Not a substitute for professional medical advice, diagnosis or treatment.

Also works as:body fat percentage

How it works

When to use it

  • Estimate body fat with a tape measure when you don't have a body-fat scale.
  • Track changes during a training program.

Formula

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) + 0.221 × log₁₀(height)] − 450

U.S. Navy circumference method, measurements in cm (inches are converted).

Worked example

Given: Male, 69 in tall, 160 lb, waist 34 in, neck 15 in

  1. In cm: height 175.26, waist 86.36, neck 38.10.
  2. Plug into the formula: about 17.9% body fat.

Result: ≈ 17.9% body fat (about 28.6 lb of fat), at the top of the ACE “Fitness” band for men.

Reading the result

  • Measure waist at the navel (women: narrowest point), neck below the larynx, hips at the widest point.
  • Trends over time matter more than one reading.

Limitations

  • Typical error is about ±3–4 percentage points.
  • DEXA or hydrostatic weighing is more accurate. Not a medical assessment.

Sources

  • Hodgdon JA, Beckett MB. Naval Health Research Center, 1984.
  • American Council on Exercise body fat categories

How to use

  1. 1Choose sex and enter height and weight.
  2. 2Measure waist and neck (and hip for women).
  3. 3Read the estimated body fat and category.

FAQ

Where do I measure my waist?

Men at the navel, women at the narrowest point, relaxed after a normal exhale.

How accurate is it?

It is an estimate, typically within 3–4%. It is most useful for tracking change over time.

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