Porosity

Porosity is expressed as the volume not occupied by solid material

n = V_v / V

   = 1 - ρ_bulk  / ρ_solid                                   (1)

where

n = porosity

V_v = void volume (m³, ft³)

V = total volume (m³, ft³)

ρ_bulk = bulk density (kg/m³, slugs/ft³)

ρ_solid = solid density (kg/m³, slugs/ft³)