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Nuclear density compaction calculator
Enter the gauge wet density and moisture, the Proctor MDD and OMC, and the required compaction. You get dry density, percent compaction, pass or fail, and an optional moisture window check. The standard count section compares today's counts with the previous four.
By ProofGrit Editorial TeamLast reviewed:
Results update as you typeUnits: pcf, %Runs in your browser. Nothing is saved.
Key takeaways
- Pass or fail uses the compaction value as displayed to 0.1 %.
- Default standard count limits: density within 1 %, moisture within 2 % of the previous four.
- A moisture window around OMC is a separate check from compaction.
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How it's calculated
How is the result calculated?
Dry density = wet × 100 ÷ (w + 100); % compaction = dry ÷ MDD × 100. Standard counts within 1 % (DS) and 2 % (MS) of the previous 4.
- 01Dry density = wet density × 100 ÷ (w + 100)
- 02% compaction = dry density ÷ MDD × 100, reported to 0.1 % and compared with the required value (default 95 %)
- 03Moisture status, when a window is entered: within OMC ± window, dry of it, or wet of it
- 04Standard count check (default limits): today's density standard within 1 % and moisture standard within 2 % of the average of the previous 4 counts
Rounding: densities to 0.1 pcf, moisture and compaction to 0.1 %. Full precision is kept between steps, and pass/fail uses the displayed value.
FAQ
Frequently asked questions about the nuclear density calculator
Does pass/fail use the rounded compaction?
Yes. Compaction is reported to 0.1 % and the comparison with the required value uses that displayed number, so the report and the decision always agree.
What if I leave the moisture window blank?
The moisture check is skipped and shown as not evaluated. Pass or fail then depends on compaction alone.
Why check standard counts every day?
A standard count that drifts from recent history can point to a gauge problem. Comparing today's counts with the average of the previous four is a quick daily check before testing.
Can I change the standard count limits?
Yes. The 1 % and 2 % defaults are editable, so you can match your lab's procedure or gauge manufacturer's guidance.
Where do MDD and OMC come from?
From a laboratory Proctor test on the same material. The Proctor curve calculator can help you find them.
Related guides and pages
- Nuclear density test: field compaction with ASTM D6938How the nuclear gauge test works, the dry density and percent compaction math, the daily standard count check, and the mistakes that cause retests.
- The Proctor test: how it works and how to read the curveWhat a Proctor test measures, how each compaction point is calculated, how the curve gives MDD and OMC, and how the zero air voids line keeps you honest.
- Sand cone test: ASTM D1556 procedure and calculationsHow the sand cone field density test works, the four-step calculation from sand in the hole to dry density, and the habits that keep results repeatable.
- Soil testing softwareHow ProofGrit handles this test in the lab.
- Standards indexEvery standard explained on this site, with plain-English purpose.
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Sources and further reading
- ASTM D6938, in-place density and water content by nuclear methodsASTM International
- U.S. Nuclear Regulatory CommissionNRC
- ASTM D698, laboratory compaction using standard effortASTM International
Standards are summarized in our own words. Read the current edition from the publisher before you test.
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