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Body Fat Calculator

Estimate your body fat percentage using the US Navy fitness formula.
Decision Context
Page-specific guidance for using this result in a real planning decision.

This calculator is designed to estimate body-fat percentage from body measurements so you can assess composition beyond scale weight alone.

Use it when you want a better planning metric for fat-loss or fitness tracking than body weight by itself can provide.

The result is best used for trend tracking under consistent measurement technique, because small taping differences can move the estimate noticeably.

Methodology, assumptions, and limitations

The estimate applies the calculator’s selected circumference-based equation to standardized body measurements. Repeating measurements under the same conditions makes trend comparisons more useful than one isolated result.

Assumptions
  • The tape is level and snug without compressing tissue.
  • Measurements are taken at the specified anatomical locations.
  • The same method is used when comparing results over time.
Limitations
  • Circumference equations estimate rather than directly measure body fat.
  • Small tape-placement differences can change the result.
  • DEXA and clinical methods may produce different values.

Sources and standards

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Calculator
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Analysis
Interpretation of the current calculator output

Enter values to see detailed analysis and insights.

How to Use

Step-by-step instructions
  1. 1Select your gender.
  2. 2Enter your height, weight, neck, and waist measurements.
  3. 3For females, also include hip measurements.
  4. 4The results will display your estimated body fat percentage and category.

US Navy Fitness Formula

The US Navy Body Fat formula is a simple method to estimate body fat percentage based on circumferences of various body parts.
BF% = 495 / (1.0324 - 0.19077 × log10(waist-neck) + 0.15456 × log10(height)) - 450

Variables:

BF%Body Fat Percentage
waistWaist circumference
neckNeck circumference
heightTotal height

Example

Standard Male Measurement

Inputs:

Height:175 cm
Weight:75 kg
Waist:85 cm
Neck:38 cm

Steps:

  1. 1.Apply log calculations based on measurements.
  2. 2.Subtract scaling factors.
  3. 3.Determine final percentage.
Result:
16.1% (Fitness Category)

Frequently Asked Questions

How accurate is this calculator?

While not as accurate as DEXA scans or hydrostatic weighing, the US Navy formula is accepted as a reliable estimation with a 3-4% margin of error for most individuals.
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Estimate body-fat percentage from measurement inputs such as waist, neck, and height so you can track composition changes beyond scale weight.