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Engineering Calculator · 118

Glass-Fiber Mass & Volume Fraction Converter

Convert glass-fiber mass percentage and volume percentage using the densities of the fiber and polymer matrix.

Thermal & material change
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Live calculation

Enter the known values.

Units remain visible beside every field and result. Change any input to recalculate immediately in your browser.

01

Inputs

02

Results

Fiber mass fraction30%
Fiber volume fraction16.079%
Theoretical void-free mixture density1.366714g/cm³

Formula
Vf=wf/ρfwf/ρf+(1−wf)/ρmV_f=\frac{w_f/\rho_f}{w_f/\rho_f+(1-w_f)/\rho_m}wf=VfρfVfρf+(1−Vf)ρmw_f=\frac{V_f\rho_f}{V_f\rho_f+(1-V_f)\rho_m}

The calculation runs locally in this browser. Values are not submitted or stored by this tool.

Direct answer

What this result means

Mass fraction and volume fraction differ when fiber and matrix densities differ. At 50% fiber by mass, with fiber density 2 g/cm³ and matrix density 1 g/cm³, the fiber occupies 33.33% of the modeled volume. Use the actual constituent densities and the declared fraction basis.

Glass-Fiber Mass & Volume Fraction Converter engineering relationship diagramThe equations use fractions from 0 to 1 internally; the form accepts percentages. Density converts each constituent mass into volume. The reported mixture density is Vfρf + (1 − Vf)ρm under a binary, void-free model, not a measured density or a prediction of material strength. This dedicated schematic represents fiber mass volume two constituent bars and is not to scale.Mass fraction w_fVolume fraction V_fFiber density ρ_fMatrix density ρ_mTWO-CONSTITUENT MIXTURE · TOOL 118Known fraction basisFiber mass fraction
Calculator-specific engineering relationship diagram — schematic, not a product drawing, and not to scale.

Formula & theory

Make the assumptions visible.

The equations use fractions from 0 to 1 internally; the form accepts percentages. Density converts each constituent mass into volume. The reported mixture density is Vfρf + (1 − Vf)ρm under a binary, void-free model, not a measured density or a prediction of material strength.

Calculation relationship
Vf=wf/ρfwf/ρf+(1−wf)/ρmV_f=\frac{w_f/\rho_f}{w_f/\rho_f+(1-w_f)/\rho_m}wf=VfρfVfρf+(1−Vf)ρmw_f=\frac{V_f\rho_f}{V_f\rho_f+(1-V_f)\rho_m}

The equations use fractions from 0 to 1 internally; the form accepts percentages. Density converts each constituent mass into volume. The reported mixture density is Vfρf + (1 − Vf)ρm under a binary, void-free model, not a measured density or a prediction of material strength.

Variables

VfFiber volume divided by total constituent volumefraction
ρmDensity of the polymer matrix constituentg/cm³

Use sequence

From measurement to review

  1. Confirm the declared reinforcement fraction and whether the compound can be treated as fiber plus matrix.
  2. Enter the known percentage and constituent densities in the same units.
  3. Retain the fraction basis and compare measured compound properties separately.

Limits

What this calculation does not confirm

  • The model contains only fiber and matrix, with additive constituent volumes and no voids.
  • Additional fillers, flame retardants, moisture, sizing and porosity need a more complete composition model when significant.
  • The conversion does not predict fiber orientation, molding quality, tensile strength, temperature rating or finished gland performance.

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Tensile stress and elongation

Normalize tensile force by original specimen area and measured extension by original gauge length.

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Calculator FAQ

Use the number without losing the engineering context.

These answers clarify what the tool calculates and where a product-specific review still begins.

01Calculator guidanceIs GF30 necessarily 30% fiber by volume?

Do not assume that basis from the abbreviation alone. Confirm the material supplier’s declaration. Reinforcement is commonly specified by mass, and a volume conversion requires the constituent densities.

02Calculator guidanceCan a glass-fiber fraction conversion predict the gland’s mechanical strength?

No. Fiber length, orientation, matrix grade, moisture, molding conditions and part geometry affect strength. Use measured properties of the specified compound and tests of the complete product.

03Calculator guidanceWhy can measured composite density differ from this fiber-mixture result?

Voids, moisture, extra constituents and temperature can change density. Check the full formulation and density test before attributing a discrepancy to reinforcement content.

Product selection support

Connect the calculation with cable-entry product options.

Bepto Cable Glands can help relate a preliminary result to the product family and current model information for your application. You can start with the details you have; a complete drawing package is not needed to ask a question.

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