Excavation Calculator
Calculate the bank and loose (hauled) volume of a dig in cubic yards, plus the number of truckloads, from length, width, depth and swell.
How it works
bank yd³ = length × width × depth ÷ 27 · loose yd³ = bank × (1 + swell%) · truckloads = ceil(loose ÷ truck capacity)
The in-ground volume — “bank” measure — is just length × width × depth divided by 27 to get cubic yards. But soil bulks up when it is dug and loosened, so the volume you actually haul away is larger by a swell factor of roughly 20–30% for most soils (more for clay, less for sand). Truckloads are the loose volume divided by the truck’s capacity, rounded up, because you cannot send a fractional load.
Worked example
A 20 × 10 ft hole 3 ft deep is 20 × 10 × 3 = 600 cu ft, ÷ 27 = 22.2 bank cubic yards. At a 25% swell that becomes 27.8 loose yards to haul — on a 10 yd³ truck, 3 loads.
Frequently asked questions
What is a swell factor?
When soil is excavated it loosens and takes up more space than it did compacted in the ground. That expansion — the swell factor — is typically 20–30%: about 25% for common soil, less for sand and gravel, more for dense clay. It matters because trucks and disposal are billed on the loose, hauled volume, not the in-ground volume.
Do I dig for more than the finished dimensions?
Usually yes. Excavations need working room and, in most soils, sloped or benched sides for safety, so the actual dig is wider than the footing or foundation it holds. Add for over-dig and confirm shoring or slope requirements — trench safety is a serious code matter.
How do I estimate backfill?
Backfill is the dug volume minus whatever the foundation, pipe or structure occupies. Reused soil compacts back down (a shrink factor), so you often need less than the loose pile — or import fill if the native soil is unsuitable. Plan both the export and any import.
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Estimate for planning. Add a waste margin and confirm against your supplier specs and local building codes.