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Standard/Modified Proctor Compaction Percentage Calculator

Check a compacted fill's field density against its laboratory maximum Proctor density.

Computed in your browser — nothing you enter is uploaded. Figures are presented in United States units and terminology, and each formula’s basis is cited under regulatory standards below.

Last verified 2026-08-27 · v1.1.0

Market
Imperial · sales tax

Percent compaction achieved

95 %

Low confidence

FAILS the specified minimum — additional compaction passes, moisture conditioning (the soil may be too dry or too wet of optimum), or a different lift thickness may be needed.

Specified minimum
95 %

At the values currently entered, the percent compaction achieved works out to 94.9 %. The largest intermediate quantity is specified minimum, at 95 % — check that step first if the total looks off. Confidence on this run is low: check the result against a supplier quote or a professional before ordering or building. Figures are shown in United States units and terminology; switch the market above if you are building elsewhere.

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.

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.

Regulatory standards & verification citations

  • Standard compaction QC check: percent compaction = (field dry density / laboratory maximum Proctor dry density) x 100; most specifications require 90-98% depending on the application

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Frequently asked questions

What's the difference between Standard and Modified Proctor?
Modified Proctor (ASTM D1557) uses significantly higher compactive energy than Standard Proctor (ASTM D698), producing a higher maximum density for the same soil — always confirm which test your project specification references, since mixing them up gives a misleading compaction percentage.
Why would compaction fail even with a lot of rolling passes?
Soil compacts best near its optimum moisture content — soil that's too dry or too wet resists reaching maximum density no matter how much compactive effort is applied, so moisture conditioning is often the real fix, not just more passes.
What compaction percentage is typically required?
It varies by application and local code: structural fill under footings often requires 95-98%, general fill 90-95%, and pavement subgrade commonly 92-95% — always follow your project's specific geotechnical specification.