How to calculate excavation volume
Excavation is measured by volume, in cubic yards. For a rectangular dig:
Cubic yards = length × width × depth (all in feet) ÷ 27
That gives the bank volume — the size of the hole, with the soil still packed in the ground. It's the number you start from for both the dig and what you'll haul away.
Soil swell: why you haul away more than you dig
Dig soil out and it loosens and expands, so the pile you truck away is bigger than the hole you made. That increase is called swell (or bulking), and it depends on the material:
| Material | Typical swell |
|---|---|
| Sand & gravel | 10–18% |
| Common earth / loam | 20–30% |
| Clay | 30–40% |
| Blasted rock | 50–60% |
So 27 cubic yards in the ground can become 33 or more loose cubic yards on the truck. This calculator applies your swell percentage to estimate the loose haul-away volume and the truckloads.
Truckloads & disposal
- Truck capacity. A standard tandem dump truck holds about 10–16 cubic yards. Bigger trucks mean fewer trips but can't reach every site.
- Soil is heavy. In-ground soil runs roughly 1.3–1.5 tons per cubic yard, so trucks often hit their weight limit before they're full — confirm with your hauler.
- Disposal adds up. Dump fees and haul distance drive the cost. Clean fill is sometimes free to drop off; mixed or contaminated soil costs more.
Before you dig
- Call 811 first. Have utilities located before any digging — it's free and required in most areas. Hitting a gas or power line is dangerous and expensive.
- Add working room. Footings and foundations need extra width beyond the structure for forms and access, so dig a bit larger than the finished size.
- Mind the walls. Deep excavations need sloped or benched sides to keep them from collapsing — never enter an unprotected trench.
Dig by hand or rent a machine?
The crossover point is roughly a few cubic yards. Small jobs — a footing trench, a handful of postholes, the edge of a small pond — are reasonable with a shovel, a mattock, and a wheelbarrow. Once you're moving 5+ cubic yards, or digging in clay, rock, or roots, a rented mini-excavator or skid steer pays for itself fast: a machine that costs $250–$400 a day can do in an hour what takes a crew all weekend by hand. Factor in haul-off too — the loose-volume and truckload figures above tell you how many trips, or what size dumpster, you'll need.
What to do with the dirt
- Reuse it on site. Regrade low spots, build a berm, or backfill elsewhere — moving dirt across your own yard is free.
- Give away clean fill. Clean fill dirt is often wanted by neighbors or listed free locally, which saves the dump fee.
- Save the topsoil. Strip and stockpile the dark topsoil before you dig, then spread it back for lawns and beds — it's the most valuable layer.