CalculationTime

Body Fat Percentage Calculator

Estimate body fat percentage from circumference measurements using the U.S. Navy method for adults.

Live math canvas

Your numbers, formula and explanation together

Body Fat Percentage Calculator: 18.8% body fat. U.S. Navy circumference estimate from height, neck and waist. Measurement consistency matters more than decimal precision.

Formula applied

The exact method behind this answer

CalculationTime keeps the method visible so the number can be checked instead of blindly trusted.

Male: 86.010 log10(waist − neck) − 70.041 log10(height) + 36.76. Female: 163.205 log10(waist + hip − neck) − 97.684 log10(height) − 78.387.
  1. Apply the formulaMale: 86.010 log10(waist − neck) − 70.041 log10(height) + 36.76. Female: 163.205 log10(waist + hip − neck) − 97.684 log10(height) − 78.387.18.8% body fatU.S. Navy circumference estimate from height, neck and waist. Measurement consistency matters more than decimal precision.

Your live breakdown

Current inputs in the calculation

These values come from the controls above and update when the calculator changes.

Formula sex
Male formula
Height
178 cm
Neck circumference
40 cm
Waist circumference
90 cm
Hip circumference
100 cm

Resulting answer

18.8% body fat

U.S. Navy circumference estimate from height, neck and waist. Measurement consistency matters more than decimal precision.

Answer
18.8% body fat
Live support
U.S. Navy circumference estimate from height, neck and waist. Measurement consistency matters more than decimal precision.

Assumptions used

What this answer assumes

The visible assumptions define the boundary of this calculation.

  • Measurements must be consistent and positive.
  • Circumference estimates are approximate and can differ from lab methods.
  • This is health education only, not diagnosis.

Master’s Tip

How to use the result well

Master’s Tip: measurement consistency matters more than decimal precision; use the same tape position each time.

Printable record

What belongs in the saved calculation

Save the inputs, result, formula, assumptions, page URL and date together so the calculation can be reviewed later.

Formula sex
Male formula
Height
178 cm
Neck circumference
40 cm
Waist circumference
90 cm

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Explain it like I'm 12

The body fat calculator converts circumferences to inches and applies the U.S. Navy circumference equations for adult body-fat estimation.

Formula

Male: 86.010 log10(waist − neck) − 70.041 log10(height) + 36.76. Female: 163.205 log10(waist + hip − neck) − 97.684 log10(height) − 78.387.

Worked example

For a male-formula adult at 178 cm height, 90 cm waist and 40 cm neck, the equation estimates about 21% body fat.

Professional note

Master’s Tip: measurement consistency matters more than decimal precision; use the same tape position each time.

Regional and unit assumptions

U.S. Navy circumference method converted from centimetres to inches.

Assumptions and limitations

Methodology & Accuracy

How this calculator is checked

CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.

Formula used

Male: 86.010 log10(waist − neck) − 70.041 log10(height) + 36.76. Female: 163.205 log10(waist + hip − neck) − 97.684 log10(height) − 78.387.

Standard or basis

U.S. Navy circumference method converted from centimetres to inches.

Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.

Master's Tip

Master’s Tip: measurement consistency matters more than decimal precision; use the same tape position each time.

Questions

Is the Navy method exact?

No. It is a field estimate and can differ from DEXA, hydrostatic weighing or clinical assessment.

Why do measurements matter so much?

Small differences in tape position can change the circumference inputs and therefore the estimate.