Porosity and Permeability Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Fluid calculations are especially sensitive to density, viscosity, geometry, pressure conventions, and unit systems. Porosity and Permeability Calculator narrows that problem to the relationship used on this page, making the displayed permeability easier to audit against the inputs and the governing equation.

What this calculator does

The Porosity and Permeability Calculator uses Pressure in, Pressure out, Distance (L), Area (A), Discharge (Q) to estimate the page’s Permeability from the fluid-mechanics relationship below. It is meant for a defined geometry and property set, so the useful part is not just the headline number but also whether your density, viscosity, dimensions, pressure reference, and flow convention match the model.

How to use it

Start with the fields that actually drive this result: Pressure in, Pressure out, Distance (L), Area (A), Discharge (Q), Viscosity (μ). Keep units consistent with the menus beside the fields and avoid mixing values measured under different conditions. After calculating, change one input at a time if you are comparing scenarios; that makes cause-and-effect much easier to see.

How the calculation works

Despite the broad title, the current form calculates permeability from Darcy flow: k = QμL/(AΔp). It does not presently calculate porosity from pore/solid volumes.

Example

With Q = 1×10⁻⁶ m³/s, μ = 0.001 Pa·s, L = 0.1 m, A = 0.01 m², and Δp = 100,000 Pa, the Darcy rearrangement gives k = 1×10⁻¹³ m². That is a permeability example only; the current form does not calculate porosity.

How to interpret the result

Interpret the Permeability within the fluid, geometry, pressure reference, and property values you entered. A numerically plausible answer can still be physically wrong if gauge/absolute pressure, diameter/radius, viscosity type, or unit convention is mismatched, so compare the result with the assumptions as well as the formula.

Limitations and notes

The current form does not contain porosity inputs or calculate porosity despite the page title; it is presently a Darcy-permeability calculation. Do not infer pore fraction from its permeability output.