EngineerHub.orgHow to use this calculator
Follow the three steps below. Start with the example values, replace them with your own data, and read the result together with the assumptions and limitations.
Inputs
| Point | Wet soil mass, kg | Moisture, % | Dry density, kg/m³ |
|---|---|---|---|
| 1 | — | ||
| 2 | — | ||
| 3 | — | ||
| 4 | — | ||
| 5 | — |
Results
Moisture–dry-density plot
The points below are plotted exactly as entered. The highlighted point is the highest measured dry density. No curve fitting or laboratory correction is applied.
How to interpret the test
- MDD is the highest dry density identified from the entered data.
- OMC is the moisture content at that highest entered point.
- Percent compaction compares field dry density with the laboratory MDD.
- Field moisture versus OMC helps show whether the field soil is wetter or drier than the entered optimum point.
| Result | Meaning |
|---|---|
| Below target | Entered field dry density does not meet the selected requirement. |
| At or above target | Calculated value meets the entered percentage, subject to test validity and project acceptance. |
| Wet of OMC | Field moisture is higher than the moisture content at the highest entered test point. |
| Dry of OMC | Field moisture is lower than that point. |
Background
Engineering basis, equations, interpretation and limitations for Proctor compaction data and field percent compaction.
ρwet = mwet / V
ρdry = ρwet /(1+w)
Percent compaction = ρdry,field / MDD × 100%
Moisture content w is entered as a percentage and converted to a decimal for calculation. The field dry density is calculated from the entered field wet density and field moisture content using the same dry-density relation.
This calculator reports the highest entered dry-density point as maximum dry density (MDD) and reports the moisture content at that same point as optimum moisture content (OMC).
It does not fit a smooth Proctor curve, interpolate a peak between measurements, apply oversize-particle corrections, or determine whether the laboratory test itself satisfies a particular standard.
Percent compaction compares the calculated field dry density with the laboratory reference MDD. A result at or above the entered target means the numerical comparison meets that target.
Actual acceptance still depends on the project specification, test method, soil zone, sampling validity, measurement uncertainty and any required correction procedures.
Ensure the mold tare has been removed from the entered wet soil mass and that mold volume corresponds to the actual laboratory mold used. Field wet density and moisture content must represent the same test location and material condition.
Use the page for calculation, checking and preliminary interpretation of entered Proctor data. Formal laboratory reporting and construction acceptance should follow the specified standard and project requirements.
Frequently Asked Questions
Common questions about Proctor test results, maximum dry density, optimum moisture content and field compaction.
MDD is maximum dry density. OMC is the moisture content associated with the maximum dry-density condition. This page uses the highest entered test point rather than fitting a curve between points.
No. It calculates and reviews entered data. Formal Proctor testing, curve interpretation, correction procedures and reporting must follow the required laboratory standard and project specification.
Acceptance criteria vary by specification, soil zone, material type and project. The calculator intentionally requires you to enter the applicable project target rather than assuming one universal value.
A laboratory report may fit a smooth compaction curve and estimate the peak between measured points. This calculator intentionally reports only the moisture content of the highest entered discrete point.
“Wet of OMC” means the entered field moisture content is above the moisture content at the highest entered Proctor point. “Dry of OMC” means it is below that value.