Abstract: Compaction performance follows a well behaved response curve for a particular material condition/compaction machine combination. Accordingly, a compaction response curve is determined from measured values representative of material density after a first and second pass by a compaction machine. The response curve is used to predict the number of passes required by the compaction machine to reach a desired density for the material, and thereby avoid making unneeded additional machine passes or passes which would not be effective due to diminished returns. The system may provide an indication when required compaction will not be achieved or will require an excessive number of passes, i.e. such as happens when moisture content of the material is high.