Soil testing software
Soil testing software for Proctor and field density
Proctor curves with MDD, OMC and the zero air voids line, nuclear density compaction with the daily standard count check, sand cone and sieve analysis. Geotechnical testing math for small labs, in pcf, percent and pounds.
Free calculators. No sign-up. They run in your browser and save nothing.
By ProofGrit Editorial TeamLast reviewed:
Key takeaways
- Proctor fit: 2nd order for 3 points, 3rd order for 4 or more.
- Percent compaction = dry density ÷ MDD × 100, decided on the value reported to 0.1 %.
- Daily standard counts are compared with the average of the previous four: 1 % density, 2 % moisture by default.
- Free USCS, Atterberg and moisture content calculators cover classification arithmetic.
Calculated live by the library
What does a reviewer see for each test?
- Dry density
- 113.6 pcf
- Compaction (req. 95 %)
- 96.3 %pass
- Density standard vs previous 4
- 0.9 %pass
- Moisture standard vs previous 4
- 2.5 %fail
- Proctor wet density
- 125.7 pcf
- Proctor dry density
- 112.2 pcf
- Zero air voids, Gs 2.70
- 127.3 pcfbelow line
- Sand cone hole volume
- 0.0530 ft³
- Sand cone dry density
- 112.5 pcf
How we handle the math
How does ProofGrit handle the math?
Every calculator on this site uses one tested calculation library. The rules below are the ones it follows.
- 01
Curves that admit their limits
Second-order fit for three points, third-order for four or more. If the peak sits at the edge of your data, you are told to add a point.
- 02
Zero air voids as a sanity check
Every Proctor point is compared with the zero air voids line for your Gs, and points above it are flagged.
- 03
Standard counts against history
Today's density and moisture standards are compared with the average of the previous four, with editable limits.
- 04
Decisions match the report
Densities to 0.1 pcf, moisture and compaction to 0.1 %. Pass or fail uses the displayed value.
Free tools
Which free calculators cover this work?
- Proctor curve calculator: maximum dry density and OMCWet and dry density per point, a fitted moisture-density curve with zero air voids line, MDD and OMC.
- Nuclear density compaction calculatorDry density, percent compaction, moisture status and the daily standard count check for nuclear gauge tests.
- Sand cone density calculatorSand in the hole, hole volume, wet and dry density and percent compaction for the sand cone test.
- USCS soil classification calculator (ASTM D2487)Group symbol, basic group name and the decision path from gradation and Atterberg limits, with a plasticity chart.
- Atterberg limits calculator: liquid limit, plastic limit and PIMultipoint liquid limit from a least-squares flow curve, plastic limit from trials, plasticity index or NP, and a plasticity chart.
Guides
Which guides explain the methods?
- 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.
- Standard vs Modified Proctor: ASTM D698 and D1557 comparedHow Standard (D698) and Modified (D1557) Proctor differ in rammer, drop and layers, why Modified gives a higher MDD, and why the right reference matters.
- 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.
- 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.
- CMT lab accreditation: AASHTO R18, ISO/IEC 17025 and recordsWhat AASHTO re:source accreditation, AASHTO R18 and ISO/IEC 17025 mean for a small CMT lab, and the records your lab and its software need to keep.
FAQ
Frequently asked questions
What can I use today?
Free calculators for Proctor curves, nuclear density compaction, sand cone, sieve analysis, USCS classification, Atterberg limits and soil moisture content, plus the soils guides on this page. They run in your browser.
Are my results saved?
No. Nothing is stored. Copy or print results into your own records.
Does it support Standard and Modified Proctor?
Yes. Choose D698 or D1557, with the 4-in (1/30 ft³) or 6-in (0.075 ft³) mold, or a custom volume. The density math is the same for both methods.
Can I change the standard count limits?
Yes. The defaults are 1 % for density and 2 % for moisture, and both are editable in the calculator.
Does it replace gauge licensing or safety procedures?
No. It only does the arithmetic. Gauge licensing, training and handling follow your license and regulators.
Wondering if ProofGrit fits your lab?
Tell us what you test and how many people run it. The team replies by email.