About this tool Calculate percent compaction from field dry density and maximum dry density (MDD). This is the standard earthworks acceptance test — compare field results against the Proctor compaction test to verify fill has been adequately compacted.
Results are colour-coded: green (≥95%), amber (90–95%), red (<90%). Optionally compare field moisture content against optimum (OMC) to check if the material is being placed at a suitable moisture content.
Includes a reference table of typical compaction requirements from SHW Series 600 and BS 6031 for general fill, selected fill, capping, sub-base, and pipe surround.
How to use this tool 1. Enter field dry density — from nuclear density gauge, sand replacement, or core cutter test.
2. Enter MDD — from the Proctor compaction test (BS 1377-4).
3. Optionally enter MC and OMC — to check placement moisture relative to optimum.
Technical information % Compaction = (field dry density / MDD) × 100
Typical requirements: ≥95% for structural/selected fill and sub-base (SHW Cl. 612/803), ≥90% for general fill and pipe surround.
Limitations Assumes field density is expressed as dry density. If bulk density is measured, convert using moisture content before entering.
MDD depends on the compaction effort (2.5kg or 4.5kg rammer, BS 1377-4). Ensure the field test reference matches the specified compaction standard.
Revision history 23 June 2026: Initial release
Disclaimer This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.
Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.
All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.
By using this tool, you accept full responsibility for how you interpret and apply the information provided.
Spotted an error? Let us know .
