Body Fat Percentage Calculator (US Navy Method)

Measure body fat percentage, lean muscle mass, and fat mass using circumference measurements standardized by the US Navy.

Free & Instant•Version: US-Navy-2024•Formula, examples and assumptions

Calculator InputsFormula US-Navy-2024

Sex

Body Weight (kg)(kg)

Height (cm)(cm)

Neck Circumference (cm)(cm)

Waist Circumference (cm)(cm)

Hip Circumference (Women Only)(cm)

Calculated Output

Estimated Body Fat

21.0%

Classification CategoryAcceptable

Total Fat Mass17.2 kg

Lean Muscle / Bone Mass64.8 kg

Instant Browser CalculationNo Server Logging

Formula & Methodology

Men: 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76; Women: 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387

Variables:

Neck Circumference: Measured just below the larynx
Waist Circumference: Measured at the navel for men, narrowest point for women

Worked Example

A 180cm male weighing 82kg with 40cm neck and 85cm waist has approximately 14.8% body fat (12.1kg fat mass, 69.9kg lean mass).

Target Audience:

Athletes, bodybuilders, military recruits, and weight loss participants.

Common Pitfalls to Avoid

Pulling the measuring tape too tight or flexing during measurement.

Important Limitations

Has a standard margin of error of ±3% compared to DEXA scans.

Frequently Asked Questions

What is an athletic body fat range?

6% to 13% for men; 14% to 20% for women.

Want deeper statutory analysis?Read related guides →

Formula and method

Men: 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76; Women: 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387

Far more reliable than BMI for muscular individuals because it differentiates bone and muscle from adipose tissue.

Variables

Neck Circumference: Measured just below the larynx
Waist Circumference: Measured at the navel for men, narrowest point for women

Worked example

A 180cm male weighing 82kg with 40cm neck and 85cm waist has approximately 14.8% body fat (12.1kg fat mass, 69.9kg lean mass).

Who this calculator is for

Athletes, bodybuilders, military recruits, and weight loss participants.

Complete guide to the body fat percentage calculator (us navy method)

A practical explanation of the method, input choices, interpretation, and limitations for this specific tool.

What the body fat percentage calculator (us navy method) measures

Body Fat Percentage Calculator (US Navy Method) is intended for Athletes, bodybuilders, military recruits, and weight loss participants. Its purpose is to answer a defined question using the registered relationship: Men: 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76; Women: 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387. Before entering values, confirm that the quantity described by this tool matches the question you need to answer. A correct calculation can still mislead if the inputs describe a different unit, period, jurisdiction or real-world condition.

The worked example for this tool is: A 180cm male weighing 82kg with 40cm neck and 85cm waist has approximately 14.8% body fat (12.1kg fat mass, 69.9kg lean mass). Use it to understand the scale of the output and to check the direction of the calculation. It is an illustration, not a promise that every situation will produce the same result. If your circumstances differ from the example, keep those differences visible when interpreting the answer.

Inputs and preparation

This calculator asks for Sex, Body Weight (kg), Height (cm), Neck Circumference (cm), Waist Circumference (cm), Hip Circumference (Women Only). Read each label and help text before entering a value, and use compatible units wherever quantities are compared or combined. A percentage may be entered as a number such as 8 when the field expects 8%, rather than as 0.08; follow the formula and labels shown on this page. Record the source and date of inputs that can change over time.

For a useful comparison, start with a realistic baseline and change one input at a time. This helps reveal which assumptions influence the output most. Do not treat a default value as a fact about your own circumstances. Where a value is unknown, label it as an assumption and test a reasonable range instead of relying on a single precise-looking result.

Formula and worked method

The method displayed for body fat percentage calculator (us navy method) is Men: 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76; Women: 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387. Its variables are defined on this page so that you can connect each input to the part of the calculation it affects. Work through the relationship with the values from the example, keep intermediate values unrounded where practical, and round the final result to a precision appropriate to the inputs. If the output seems unexpected, verify units and order of operations first.

The result is interpreted as follows: Far more reliable than BMI for muscular individuals because it differentiates bone and muscle from adipose tissue. This interpretation matters because the formula alone may not explain every practical consequence. For example, a financial result may exclude fees or tax adjustments, while a physical measurement may depend on idealised geometry. Check the stated assumptions before comparing this output with another calculator or using it to make a decision.

Common errors and checks

The most relevant pitfalls for this calculator are: Pulling the measuring tape too tight or flexing during measurement. Check these points before accepting the result. Also confirm that every field contains the intended value, that no unit conversion has been skipped, and that zero or negative inputs are appropriate for the question. A result can be mathematically consistent while still being unsuitable if the input values do not describe the same situation.

To validate the result, reproduce the worked example, compare the output with a rough independent estimate, and then test a second scenario. If the calculator disagrees with a published standard or a reliable example, keep a record of the inputs, expected answer and source before reporting a possible defect. Do not change the inputs solely to force the result to match an expectation.

Limitations and responsible use

This tool has the following documented limits: Has a standard margin of error of ±3% compared to DEXA scans. Those boundaries should guide how much confidence you place in the result. If the real problem includes factors that the calculator does not model, treat the answer as a partial estimate and account for the missing factors separately. Extra decimal places cannot compensate for incomplete information or a simplified model.

For consequential decisions, verify current rules and source data independently. Tax and financial estimates may depend on effective dates and individual circumstances; health tools do not diagnose; and construction or scientific calculations may need applicable standards and professional review. Calcendo provides an educational calculation aid, not a guarantee or a substitute for official guidance. Use the result together with the stated formula, assumptions and limitations.

Frequently asked questions