Void Ratio Calculator

Enter soil index properties to instantly compute void ratio, porosity, degree of saturation, and dry unit weight.

Soil Index Properties

Typical range: 2.60–2.80 for mineral soils

Mass of water / mass of dry solids × 100

Typical range: 15–22 kN/m³

Computed Results

Void Ratio
— e

Porosity
— n (%)

n = e / (1 + e)

Degree of Saturation
— S (%)

S = w · Gs / e

Dry Unit Weight
— kN/m³

γd = γ / (1 + w)

Relationships Used

γd = γ / (1 + w/100)
e = (Gs · γw / γd) − 1
n = e / (1 + e)
S = (w/100 · Gs) / e

γw = 9.81 kN/m³ (SI) or 62.4 pcf (US)

Summary

Enter soil index properties to instantly compute void ratio, porosity, degree of saturation, and dry unit weight.

How it works

  1. Enter the specific gravity of soil solids (Gs), typically 2.60–2.80 for most soils.
  2. Provide the natural water content (w%) of the soil sample.
  3. Input the bulk unit weight (γ) in kN/m³ or pcf.
  4. Select your preferred unit system (SI or US Customary).
  5. Results update instantly: void ratio (e), porosity (n), degree of saturation (S), and dry unit weight (γd).

Use cases

  • Classify soil compaction state and density in geotechnical site investigations.
  • Check whether a soil sample is loose, medium dense, or dense based on void ratio.
  • Calculate degree of saturation to assess drainage and pore pressure conditions.
  • Determine dry unit weight for compaction control and earthwork design.
  • Support laboratory report preparation from standard index property tests.
  • Verify hand calculations from ASTM D7263 or AASHTO T99 test procedures.

Frequently Asked Questions

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