Body Fat Calculator

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Estimate body fat percentage with the US Navy tape method and see your fat and lean mass in kg.

Inputs

Sex

Weight (kg)

Height (cm)

Waist circumference (cm)

Neck circumference (cm)

Hip circumference (women) (cm)

How to use this calculator: Body Fat Calculator

Estimate body fat percentage with the US Navy tape method and see your fat and lean mass in kg. The example below is calculated by this page's real engine from the displayed inputs.

1Confirm that the Body Fat Calculator matches the quantity or design check you need.
2Enter Weight, Height, and Waist circumference using the units printed beside each field.
3Select the applicable Sex options; these choices change the calculation method or factors.
4Calculate, then follow the substituted equations in the worked example and compare the result with any stated limit.
5Read the assumptions, warnings and cited references before using the result for a financial, medical or engineering decision.

Input guide and example values

Use values from the same measurement basis and time period. Conditional fields appear only when the related option is selected.

Input	Example value	Why it matters
Sex	Male	Select the option that matches the real installation or scenario.
Weight	70 kg	Measured or known weight used by the calculation engine.
Height	172 cm	Measured or known height used by the calculation engine.
Waist circumference	85 cm	Measured or known waist circumference used by the calculation engine.
Neck circumference	38 cm	Measured or known neck circumference used by the calculation engine.
Hip circumference (women)	95 cm	Optional input; leave the supplied default only when it matches your case.

Formula inputs & variables for Body Fat Calculator

These are the named quantities used by this calculator. When the source formula does not define a mathematical symbol, OneCalcApp keeps the real input label instead of inventing one.

Variable / input	Unit	Meaning in this calculation
Sex	—	Select the option that matches the real installation or scenario.
Weight	kg	Measured or known weight used by the calculation engine.
Height	cm	Measured or known height used by the calculation engine.
Waist circumference	cm	Measured or known waist circumference used by the calculation engine.
Neck circumference	cm	Measured or known neck circumference used by the calculation engine.
Hip circumference (women)	cm	Optional input; leave the supplied default only when it matches your case.

How the Body Fat Calculator works

The Body Fat Calculator uses Sex, Weight, Height, Waist circumference, Neck circumference, and Hip circumference (women) to calculate Body fat, Fat mass, and Lean mass. Its engine applies Men: 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450; the worked values below come from that same live calculation rather than a separately typed example.

With Sex Male, Weight 70 kg, Height 172 cm, Waist circumference 85 cm, Neck circumference 38 cm, and Hip circumference (women) 95 cm, the main worked-example result is Body fat = 17.4%.

How each Body Fat Calculator input is used

Sex

The Body Fat Calculator worked example selects “Male”. Available choices include Male and Female. This selection may change the method or factor used by the engine, so choose the option that matches the real case.

Weight

The Body Fat Calculator worked example uses Weight = 70 kg. This value is passed directly into the calculation, with an allowed minimum 0.

Height

The Body Fat Calculator worked example uses Height = 172 cm. This value is passed directly into the calculation, with an allowed minimum 0.

Waist circumference

The Body Fat Calculator worked example uses Waist circumference = 85 cm. This value is passed directly into the calculation, with an allowed minimum 0.

Neck circumference

The Body Fat Calculator worked example uses Neck circumference = 38 cm. This value is passed directly into the calculation, with an allowed minimum 0.

Hip circumference (women)

The Body Fat Calculator worked example uses Hip circumference (women) = 95 cm. This value is passed directly into the calculation, with an allowed minimum 0.

Body Fat Calculator formulas and result interpretation

Formula 1: relationship used

In the Body Fat Calculator, Men: 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450. The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Formula 2: relationship used

In the Body Fat Calculator, Women: 495 / (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450. The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Body fat

For the displayed Body Fat Calculator worked example, Body fat is 17.4%. Fitness Verify Sex, Weight, and Height and their units before relying on this output.

Fat mass

For the displayed Body Fat Calculator worked example, Fat mass is 12.2 kg. Verify Sex, Weight, and Height and their units before relying on this output.

Lean mass

For the displayed Body Fat Calculator worked example, Lean mass is 57.8 kg. Verify Sex, Weight, and Height and their units before relying on this output.

Body Fat Calculator accuracy, checks and limitations

Body Fat Calculator units check: confirm Sex, Weight (kg), Height (cm), Waist circumference (cm), Neck circumference (cm), and Hip circumference (women) (cm) before calculating.
Body Fat Calculator result check: compare Body fat, Fat mass, and Lean mass with the substituted formula steps and the displayed rounding precision.
Body Fat Calculator: This is a general estimate, not a diagnosis or personal medical advice. Discuss health decisions with a qualified clinician.

Formula, derivation and worked example

The US Navy method uses tape measurements instead of calipers, so it is easy to repeat at home. Measure at the same time of day, relaxed, with the tape snug but not tight. Trends matter far more than any single reading.

Men: 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450

Women: 495 / (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450

Substitution steps

1. Navy formula
log-based circumference model
= 17.4%

Computed example results

Body fat: 17.4%; Fitness
Fat mass: 12.2 kg
Lean mass: 57.8 kg

Understanding the result

Read the main result together with supporting checks, assumptions, limits and intermediate values.

For a manual check, repeat the first equation, confirm the units and change one input at a time.

Assumptions and calculation scope

Weight is assumed to be entered in kg; converting from another unit before entry avoids changing the numerical meaning of the calculation.
Sex is assumed to match the real case. Choosing a different available option can change the method, factor or interpretation used by this calculator.
Body Fat Calculator applies the displayed Men: 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450 relationship to the entered health inputs. Factors that are not exposed as inputs or stated assumptions are outside this calculator's calculation scope.

Common mistakes when using Body Fat Calculator

Do not mix units for Weight (kg), Height (cm), Waist circumference (cm). A unit mismatch changes the input magnitude even when the typed number looks reasonable.
Do not leave Sex on the default choice unless that choice matches the real scenario; the selected option can change the calculation path or factor.
Do not replace the displayed Men: 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450 relationship with a different convention without also changing the underlying assumptions; compare like-for-like methods when checking the result.
Do not treat Body fat = 17.4% from the worked example as a universal answer. It belongs to the displayed example inputs and must be recalculated for the actual case.

When the Body Fat Calculator is useful

Body Fat Calculator is designed for cases where Sex, Weight, Height, Waist circumference are known and you need Body fat, Fat mass, Lean mass. The page keeps the live calculator, calculation method and worked example together so the result can be checked instead of treated as a black-box number.

Use the calculator for the scope described by its inputs and notes. The displayed method is Men: 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450. If the real project or decision needs factors that are not represented here, treat the result as an estimate and add the missing checks separately.

Sex and Weight: what changes the answer

The worked example uses Sex = Male, Weight = 70 kg, Height = 172 cm, Waist circumference = 85 cm. With those values, Body fat is 17.4%. Changing an input should be interpreted according to that field's unit, range, option and hint rather than by the number alone.

For this calculator, the main input roles are: Sex: Select the option that matches the real installation or scenario. Available choices include Male, Female. Weight (kg): Measured or known weight used by the calculation engine. Height (cm): Measured or known height used by the calculation engine. Waist circumference (cm): Measured or known waist circumference used by the calculation engine.

How to sanity-check a Body Fat Calculator result

Start by confirming the entered values and units, then compare the substituted working with the displayed formula or calculation steps. Pay particular attention to Body fat, because it is the first worked-example output shown by the live engine.

Finally, compare the result with the assumptions, warnings and related calculators on this page. A nearby calculator can be useful as a cross-check when it measures the same workflow from a different input or output direction.

Next logical calculator

Continue with BMI Calculator

Useful next check because both tools use Weight and Height, while BMI Calculator answers a different part of the same workflow.

Open BMI Calculator

Formula

Men: 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450
Women: 495 / (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450

Frequently asked questions

What inputs does the Body Fat Calculator use?

It uses Sex, Weight, Height, Waist circumference, Neck circumference, and Hip circumference (women). Follow the unit printed for each field and choose any selectable option to match the real scenario.

What does the Body Fat Calculator calculate?

It calculates Body fat, Fat mass, and Lean mass. With the displayed default inputs, Body fat is 17.4%.

Which formula does the Body Fat Calculator use?

The primary relationship is Men: 495 / (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450. The page also shows substituted values and calculation steps so the result can be checked independently.

How can I verify a Body Fat Calculator result?

First verify the units for Sex, Weight, and Height. Then compare the substituted formula steps with Body fat and its displayed precision.

What are the limitations of the Body Fat Calculator?

Body Fat Calculator: This is a general estimate, not a diagnosis or personal medical advice. Discuss health decisions with a qualified clinician.

Where can I find related Health tools?

Use the related-tools section on this page to compare another method, change units or continue the same health calculation.

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