Porosity (n or φ) is the fraction of a rock or soil sample that consists of open void space (pores). It is expressed as a percentage or decimal: n = V_void / V_total × 100%.

What is the difference between total porosity and effective porosity?

Total porosity counts all void space, including isolated pores. Effective (connected) porosity counts only the interconnected pores through which fluid can flow. This calculator computes total porosity.

How is porosity calculated from bulk and grain density?

Porosity = 1 − (ρ_bulk / ρ_grain). Bulk density is the mass of the sample divided by its total volume; grain density (particle density) is the mass divided by the solid-grain volume only.

What are typical porosity values for common materials?

Sandstone: 5–35%, Limestone: 5–20%, Shale: 1–10%, Unconsolidated sand: 25–50%, Gravel: 25–40%, Clay: 40–70%, Granite: <1%.

What units can I use for volume?

Porosity is dimensionless (a ratio), so any consistent volume unit works. This calculator accepts cubic centimeters (cm³), cubic meters (m³), milliliters (mL), liters (L), and cubic feet (ft³).

What is void ratio and how does it relate to porosity?

Void ratio (e) = V_void / V_solid. It relates to porosity by: e = n / (1 − n) and n = e / (1 + e). This calculator reports both.

What does 30% porosity mean?

A porosity of 30% means 30% of the sample's total volume is open pore space and 70% is solid grains. For example, 1 m³ of rock with 30% porosity holds up to 0.3 m³ of fluid. This is typical of good-quality reservoir sandstone or moderately packed sand.

Porosity Calculator

Name: Porosity Calculator
Availability: InStock
Author: Nham Vu

Calculate porosity as a percentage or decimal from void volume and total volume, or from bulk and grain densities.