Relative Compaction Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026Checking that fill soil is compacted enough
Relative compaction compares actual field-measured soil density against the maximum achievable dry density established in a laboratory Proctor compaction test - the standard quality control check for structural fill placement.
Worked example
For a field dry density of 1,850 kg/m³ against a maximum Proctor dry density of 1,950 kg/m³:
Relative Compaction = (1850 / 1950) x 100 = 94.87% (Below typical 95% compaction specification)
Most construction specifications require 90-95% relative compaction for structural fills - this result falls just short of a common 95% threshold, illustrating why field density testing at multiple points throughout a fill is standard practice before proceeding with construction on top of it.