ToolsSoil MechanicsPhase Relationships

Porosity Calculator

Calculate soil porosity from void ratio. Convert between void ratio and porosity for geotechnical analysis and groundwater flow calculations.

Last updated 1 April 2026

About this tool

Convert void ratio to porosity. Porosity (n) is the ratio of void volume to total volume, expressed as a decimal or percentage.

Porosity is widely used in groundwater flow calculations (Darcy's law), soil characterisation, and environmental assessments. While void ratio is more common in geotechnical engineering, porosity is preferred in hydrogeology and environmental science.

The two properties are directly interchangeable — this tool makes the conversion instant.

How to use this tool

Enter the void ratio (e) — from laboratory testing or calculated using the Void Ratio Calculator.
Read the porosity — shown as both a decimal (n) and a percentage. Compare against the typical ranges below the result.

Technical information

The tool uses the standard identity:

n = e / (1 + e) where n = porosity and e = void ratio.

This is derived directly from the phase diagram: since total volume = solid volume + void volume, dividing through by solid volume gives 1 + e, and porosity is n = Vv / Vt = e / (1 + e).

Typical porosity values

Dense gravel: 25–35%
Dense sand: 30–40%
Loose sand: 40–50%
Clay: 35–60%

Limitations

Porosity is a bulk property — it does not describe pore size distribution or connectivity, which are important for permeability and drainage behaviour.
For groundwater modelling, effective porosity (the fraction that contributes to flow) is typically lower than total porosity, particularly in clays.
The conversion assumes void ratio has been correctly determined — ensure input values come from reliable laboratory data.

Revision history

1 April 2026: Initial release.

Disclaimer

This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.

Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.

All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.

By using this tool, you accept full responsibility for how you interpret and apply the information provided.

Spotted an error? Let us know.

Void ratio (e)

Typical range: 0.3 (dense) to 1.5+ (soft clay)