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Body Fat Calculator

Estimate your body fat percentage using the US Navy fitness formula.
What This Calculator Helps You Do
Use the inputs below to test scenarios, compare outcomes, and interpret the result before acting on it.

Body Fat Calculator is designed to give you a fast answer, but it also provides supporting context such as formulas, worked examples, FAQs, and charts so the result is easier to validate.

For the best result, use realistic input values, review the assumptions in the explanation panels, and compare multiple scenarios if you are planning a decision based on the output.

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.

Calculator
Enter your values
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.
In-depth guideBrowse Health calculators
Body Fat Calculator Guide
Detailed usage notes, assumptions, mistakes to avoid, and related tools.

Body Fat Calculator helps turn the available inputs into a result that is easier to check, compare, and explain. Estimate your body fat percentage using the US Navy fitness formula.

Use this page together with BMI Calculator when your question touches related assumptions in the same health workflow. For a nearby workflow, open BMI Calculator.

Formula And Variables
How the calculator turns inputs into an answer.

US Navy Fitness Formula is the main method behind this calculator. The equation is BF% = 495 / (1.0324 - 0.19077 × log10(waist-neck) + 0.15456 × log10(height)) - 450, and the calculator applies it consistently as you change the inputs.

The most important variables are: BF% is body fat percentage, waist is waist circumference, neck is neck circumference, height is total height. Check those values first if the output looks higher or lower than expected.

How To Use The Result
What to compare before acting on the output.

The worked example on this page uses Height = 175 cm, Weight = 75 kg, Waist = 85 cm, Neck = 38 cm and produces 16.1% (Fitness Category). Use that example as a quick check for the calculation flow before entering your own values.

For practical use, read the body fat calculator result as a decision-support number. It is strongest when you compare two or more scenarios using the same units and assumptions.

Data Visualization And Analysis
Different chart views answer different questions about the same calculator output.

Best ways to read the charts

Use a bar chart when you need to compare separate result components, a line or area chart when the output changes across steps or time, and a pie-style distribution when every value is part of one total.

When the page shows multiple chart tabs, start with the overview, then check the ranking view to see which value drives the result most strongly.

What the analysis should tell you

Compare the average, range, highest value, lowest value, and dominant contributor before making a conclusion from the main number alone.

If one value contributes most of the total, test that assumption first. If values are spread evenly, the result is usually driven by the full input set rather than a single outlier.

Common Mistakes
  • Do not mix units unless the calculator explicitly converts them for you.
  • Avoid copying a result without checking whether the inputs describe the same time period, measurement system, or scenario.
  • If the answer looks surprising, change one input at a time so you can identify which assumption is driving the output.
When The Result May Be Inaccurate

The result can be inaccurate if inputs use mixed units, rounded source data, outdated rates, or assumptions that do not match the situation being modeled.

Run a second scenario with conservative inputs when the output will affect a purchase, project, health decision, academic answer, or financial plan.

Body Fat Calculator is an educational planning tool. It should not replace advice from a qualified professional who can review the full context and current rules.

Long-tail Guides For This Calculator
These pages answer more specific versions of the same search intent.
Body Fat Calculator With Measurements

Estimate body-fat percentage from measurement inputs such as waist, neck, and height so you can track composition changes beyond scale weight.

Related Calculators
Continue through the same topic cluster with crawlable internal links.
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Calorie Calculator

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Additional Questions

How accurate is Body Fat Calculator?

Body Fat Calculator is accurate for the formula and inputs shown on the page. Real-world accuracy depends on whether the values you enter are complete, current, and measured in the expected units.

What should I check before using the body fat calculator result?

Check the input units, review the formula section, compare the worked example, and run at least one alternate scenario if the result will support a decision.