Porosity and Permeability Calculator
Compute n and estimate k for granular media.
How to Use This Calculator
1
Enter densities
ρb (bulk) and ρs (particle).
2
Enter particle size
Use representative diameter for the medium.
3
Calculate
View porosity and permeability estimate.
Formulas
n = 1 − ρb / ρs
k = (dp² n³) / (180 (1 − n)²)
Where: n porosity (void fraction), k intrinsic permeability (m²).
Example: ρb=1600, ρs=2650 ⇒ n≈0.396. With dp=0.5 mm ⇒ k≈ 3.0e−10 m².
Frequently Asked Questions
Accuracy of Kozeny–Carman?
It is an estimate for packed beds of roughly spherical particles; real soils may deviate.
Units?
All inputs are SI; k is in m². Darcy unit: 1 D ≈ 9.87e−13 m².