Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

Bulk volume

Total (bulk) volume of the rock sample in cubic meters.

Pore volume

Pore (void) space volume in cubic meters.

Compute the porosity fraction and percentage of a rock sample from its pore volume and bulk volume. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Porosity fraction

Porosity as a fraction of bulk volume (dimensionless).

Porosity percent

Porosity expressed in percent.

• Geological models are scale-, site-, method-, and calibration-dependent. Heterogeneity, anisotropy, sampling, diagenesis, pressure-temperature history, instrument response, boundary conditions, and empirical-correlation range can dominate the result.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• Porosity From Bulk Density Calculator

  Compute porosity as n = 1 - (bulk density / grain density) for a rock or soil sample.

• Core Porosity Helium Calculator

  Compute helium-pycnometry porosity from bulk volume and helium-measured grain volume, both in cubic centimetres.

• Well Log Porosity Density Calculator

  Density-log porosity phi_D = (rho_ma - rho_b) / (rho_ma - rho_f) from bulk, matrix and pore-fluid densities in kilograms per cubic meter; the standard formation-density porosity relation.