Excavation Spoil Calculator
Calculate spoil volume, swell factor, lorry loads, and estimated disposal costs for any excavation. Works for trenches, pits, slopes, and circular excavations.
Spoil Calculator
Select excavation shape and enter dimensions
For a standard trench or rectangular foundation pit
Uses the prismatoid formula — average of top and bottom widths × depth × length
For soakaways, inspection chambers, cylindrical pits, or well excavations
Clay swells significantly when disturbed — bulk density approx. 1,600 kg/m³ in situ.
Typical skip/tipper disposal rates vary by region and soil classification (inert vs contaminated).
Spoil Results
Volume, swell, loads & disposal cost
Select your excavation shape, enter dimensions and soil type, then click Calculate spoil to see volume, lorry loads, and disposal costs.