Dirt gets bigger when you dig it up. This gives you the in-ground volume, the swelled loose volume you’ll actually haul, and the truckload count.
Dig details
ft
ft
ft
cu yd
Bank volume (in the ground)
—
Loose volume (what you haul)—
Truckloads—
Bank cubic feet—
"Bank" is undisturbed in-ground volume — what you quote the dig by. "Loose" is after swell — what fills the trucks. Backfilling later? Compacted material shrinks below bank volume, so you may need to import extra.
Bank vs. loose — the concept that saves the haul-off budget
Soil in the ground is compacted by centuries of weight. Break it loose and it fluffs up: sand about 12%, typical loam 25%, clay up to 35%, blasted rock 50%. Quoting trucking off the bank number is the classic rookie mistake — the pile is always bigger than the hole.
bank yd³ = L × W × D ÷ 27 · loose yd³ = bank × swell factor
Worked example
A 30 × 4 ft utility trench, 3 ft deep in loam: 360 cu ft = 13.3 bank yards → 16.7 loose yards after 25% swell — two 12-yard truckloads, not one and change. On a bigger basement dig the swell difference alone can be several entire truckloads.
Three field notes
Call 811 before any dig, every time — it's free and it's the law. Trenches 5 ft and deeper require shoring, shielding or sloping under OSHA before anyone enters. And if you're backfilling later, compacted fill occupies less than bank volume, so the dirt you swore was "all going back in the hole" often isn't enough.
Frequently asked questions
What is soil swell and why does it matter?
Excavated soil expands because digging breaks up its natural compaction — typically 12–35% depending on material. It matters because hauling, stockpile space, and truck counts are all based on the swelled (loose) volume.
How many cubic yards fit in a dump truck?
Standard tandem dump trucks carry 10–14 cubic yards; tri-axles 15–18; small single-axles 5–7. Weight limits can cap a load below its volume for wet clay or rock, so ask the hauler what they actually load.
How much does excavation typically cost?
Machine excavation commonly runs $2–8 per bank cubic yard for open digging, more for trenches, rock, tight access or hand work — plus trucking and disposal per loose yard. Get the volume right first; everything prices off it.