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Porosity And Permeability Calculator

Work out porosity and permeability instantly with clear inputs, formula shown and shareable results.

About Porosity And Permeability Calculator

Porosity is pore volume over bulk volume - 22% here. Permeability is a different property, estimated by the Kozeny-Carman relation from grain size and porosity: k = d^2 phi^3 / (180 (1-phi)^2). Because grain diameter is squared, fine sand can share a sandstone's porosity while transmitting orders of magnitude less fluid.

Formulas

Porosity

phi = pore volume / bulk volume

Kozeny-Carman permeability

k = d^2 phi^3 / (180 (1 - phi)^2)

Worked example

With the default values below, Porosity And Permeability Calculator returns Porosity of 22.00%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Bulk sample volumeminimum 0 cm3
100 cm3
Pore volumeminimum 0 cm3
22 cm3
Mean grain diameterminimum 0 mm
0.25 mm

Results

Porosity
22.00%
Estimated Permeability
6.1575 × 10⁰ D
Hydraulic Conductivity
5.9615 × 10⁻⁵ m/s
Formation Quality
Moderate

Step by step

  1. 1Values used
  2. 2Porosity
  3. 3Kozeny-Carman permeability
  4. 4Porosity= 22.00
  5. 5Estimated Permeability= 6.1575 D
  6. 6Hydraulic Conductivity= 0.0001 m/s
  7. 7Formation Quality= Moderate

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Can a rock be porous but impermeable?

Yes. Clay and chalk have high porosity but tiny, poorly connected pores, so they hold water without transmitting it.

What is a darcy?

The permeability that passes 1 cm3/s of 1 cP fluid through a 1 cm2 area under a 1 atm/cm gradient - about 9.87e-13 m2.

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