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Soil Relative Density Calculator

Classify a granular soil's compactness (loose to very dense) from its void ratio relative to its maximum and minimum possible void ratios.

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Imperial · sales tax
The void ratio in the loosest possible state, from ASTM D4254 testing.

Clean sands run 0.8 to 1.0 here, but emax has to be at least the field void ratio it is compared against, and organic soils reach well past the 1.5 this field used to cap at.

The void ratio in the densest possible state, from ASTM D4253 testing.

Organic, peaty and highly compressible soils sit well above a void ratio of 1 even in their densest state, so this field runs to 3 — the same ceiling as emax and the field value, since all three describe one soil.

The soil's actual void ratio in the field.

See the Soil Void Ratio Calculator, which derives it from the dry unit weight and the specific gravity of the solids. It has to sit between emin and emax for the result to mean anything — all three describe the same soil, so if the field value falls outside the laboratory pair, one of the three belongs to a different sample.

Relative density

62.5 %

High confidence

Classification: Medium dense.

Field void ratio
0.6
Range between emin and emax
0.4
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Standard relative density formula: Dr = (emax − e) / (emax − emin) x 100%, where emax and emin are determined from standard maximum/minimum density lab tests (ASTM D4253/D4254)

Inputs used

Maximum Void Ratio (emax)
0.85
Minimum Void Ratio (emin)
0.45
Field (In-Situ) Void Ratio (e)
0.6

Intermediate steps

Field void ratio
0.6
Range between emin and emax
0.4
Final result62.5 %

Confidence note: Classification: Medium dense.

What this calculation does not cover

  • This is a packing index, not a strength or a design value. It returns no bearing capacity, settlement, friction angle or liquefaction resistance — relative density is an input to those analyses, not a substitute for any of them.
  • It is not a compaction acceptance test. Percent compaction against a Proctor maximum (ASTM D698 or D1557) is measured from a different reference state, there is no general conversion between the two scales, and a fill can pass one specification clause while failing the other.
  • The consistency check only confirms the field value sits between emin and emax. It cannot see index limits run on a different sample, a specific gravity borrowed from another test, or a grading that drifted between the laboratory sample and the material actually placed, and it describes one void ratio at one location and depth rather than the fill as built.
  • emax and emin are not material constants. They move with mould size, vibration amplitude and duration, moisture condition and operator, and repeat testing between laboratories scatters them; none of that scatter is carried into the percentage, and the classification bands have hard edges that a hundredth of a void ratio can cross.
  • The index tests behind emax and emin are written for free-draining cohesionless soils with only a small fines fraction — roughly 15 percent passing the No. 200 sieve in ASTM D4253 and D4254. Silts, clays, organic soils and sands with substantial fines fall outside those methods; the arithmetic still returns a percentage for their numbers and it is not a relative density.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-03 · in the site-wide review of 2026-09-06 · v1.0.1

Regulatory standards & verification citations1
  1. Standard relative density formula: Dr = (emax − e) / (emax − emin) x 100%, where emax and emin are determined from standard maximum/minimum density lab tests (ASTM D4253/D4254)

Which documents these citations point at

Standards referenced: ASTM D4253 (ASTM International, United States).

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

  • Reading a Soil Reportuses this calculator

    A lab sheet gives specific gravity and dry density; a wall check wants moist and buoyant unit weight. The conversion between them, and where it goes wrong.

Called something else where you work? Trench support — the term in each market, how close the equivalence really is, and the standard that governs it.

Still deciding? SPT N-Value vs Relative Density — the factors that actually differ, with no invented prices.

How to calculate soil relative density in 4 steps

  1. Maximum Void Ratio (emax)The void ratio in the loosest possible state, from ASTM D4254 testing.
  2. Minimum Void Ratio (emin)The void ratio in the densest possible state, from ASTM D4253 testing.
  3. Field (In-Situ) Void Ratio (e)The soil's actual void ratio in the field.
  4. Relative densityThe tool computes the relative density from those figures and shows the formula, its sources, and a confidence rating alongside it.

Frequently asked questions

What soil types is relative density used for?
It's specifically for granular (cohesionless) soils like sand and gravel — cohesive soils (clay) use different consistency measures (like liquidity index) since their behavior isn't governed the same way by packing density.
Why does relative density matter for construction?
It directly relates to bearing capacity, settlement behavior, and liquefaction susceptibility during earthquakes — denser sand is generally stronger, less compressible, and less prone to liquefaction than loose sand.
How do I get emax and emin values?
From standard laboratory tests (ASTM D4253 for maximum density/minimum void ratio, ASTM D4254 for minimum density/maximum void ratio) performed on a representative sample of your specific soil.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.