What is the relationship between void ratio and porosity?

Void ratio (e) is the ratio of void volume to solid volume: e = Vv/Vs. Porosity (n) is the ratio of void volume to total volume: n = Vv/V. They are related by n = e / (1 + e) and e = n / (1 − n).

What are typical void ratio and porosity values for common soils?

Loose sand: e ≈ 0.65–0.85 (n ≈ 39–46%). Dense sand: e ≈ 0.35–0.55 (n ≈ 26–35%). Soft clay: e ≈ 0.9–1.4 (n ≈ 47–58%). Gravel: e ≈ 0.30–0.50 (n ≈ 23–33%).

Can void ratio be greater than 1?

Yes. A void ratio greater than 1 means there is more void space than solid material by volume. This is common in soft clays and organic soils. Porosity, however, is always between 0 and 1 (or 0% and 100%).

Why does the porosity formula use (1 + e) in the denominator?

Because total volume V = Vs + Vv = Vs(1 + e) when Vs = 1 by convention. Dividing void volume (e) by total volume (1 + e) gives porosity n = e / (1 + e).

Is this tool suitable for professional geotechnical calculations?

Yes for the conversion step. These are fundamental, exact algebraic identities from soil mechanics (e.g., Das, Coduto). Always verify final designs against applicable standards (AASHTO, Eurocode 7, local codes).

Porosity from Void Ratio Calculator

Name: Porosity from Void Ratio Calculator
Availability: InStock
Author: Nham Vu

Enter void ratio to get porosity, or enter porosity to get void ratio — instant two-way conversion for soil mechanics.

Conversion Input

Convert from

Void Ratio (e) — dimensionless

Enter a value > 0. Typical void ratio range: 0.3 – 1.5.

Formula applied

n = e / (1 + e)

Result

Enter a value and click Calculate.

Typical Values for Common Soils

Soil Type	Void Ratio (e)	Porosity (n)

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Summary

Enter void ratio to get porosity, or enter porosity to get void ratio — instant two-way conversion for soil mechanics.

How it works

Choose a conversion direction: void ratio to porosity, or porosity to void ratio.
Enter the known value in the input field.
Results appear instantly using the standard formulas: n = e / (1 + e) and e = n / (1 − n).
Use the reference table to cross-check typical values for common soil types.
Copy the result for use in reports or further calculations.

Use cases

Convert lab-measured void ratio to porosity for reporting and design.
Back-calculate void ratio from porosity data published in soil surveys.
Verify hand calculations in geotechnical lab reports and site investigation summaries.
Support classroom and exam preparation for soil mechanics courses.
Check porosity bounds when classifying soils as loose, medium dense, or dense.
Quickly explore how changes in void ratio affect soil porosity during consolidation.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu