Excavation and Haul-Off Calculator

What this calculator does

You give it the dimensions of the hole and the kind of soil you are digging. It returns the in-place volume, the swelled volume that actually rides in the truck, the weight in tons, how much you are keeping on site as backfill, the net material leaving, how many truckloads that is, and what the haul costs.

The gap between the first two numbers is the point of the whole exercise, and it is the reason excavation quotes surprise people.

Bank yards and loose yards are different numbers

Soil in undisturbed ground has been compressed by its own weight and by geological time. Dig it out and it fluffs — the grains no longer nest, air fills the voids, and the same material occupies noticeably more space.

The industry has names for the three states:

• Bank cubic yards (BCY) — volume in place. This is the size of the hole, and it is what you calculate from dimensions.
• Loose cubic yards (LCY) — volume after excavation. This is what fills the truck and what haul-off is priced on.
• Compacted cubic yards (CCY) — volume after being placed and compacted again, which is less than bank.

Typical swell from bank to loose runs 12 percent for sand, 25 percent for topsoil and common earth, 30 percent for clay, and up to 50 percent for blasted rock. So a 100-cubic-yard basement excavation in clay produces about 130 cubic yards of material to move — ten or eleven tandem loads instead of eight.

That gap is where “the excavation quote came in higher than my math” almost always lives.

Weight is usually the real constraint

A tandem dump truck rated for 14 cubic yards will very rarely leave a site with 14 cubic yards of clay in it, because it will hit its legal axle weight first.

Rough in-place weights per cubic yard: topsoil 2,400 lb, common earth 2,800, clay 3,000, sand and gravel 3,200, rock 4,000. Wet material adds 20 to 30 percent. A 14-yard box of wet clay is well over 20 tons of payload, which no tandem is legal to carry.

Which is why the tonnage figure this calculator gives you matters as much as the yardage. If haul-off is quoted per ton — common — the weight is the price. If it is quoted per load, the weight decides how full each load can actually be, and an experienced hauler prices accordingly.

Backfill: material that never leaves

Not everything you dig gets hauled. Foundation excavation typically returns a large share of the spoil to the hole once the walls are up, and utility trenches are usually backfilled with their own spoil apart from a stone bed.

Set the backfill percentage and the calculator subtracts it before working out loads, because paying to haul soil off site and then paying again to bring soil back is a distressingly common way to spend money.

Two cautions. Topsoil should be stripped and stockpiled separately — it is the most valuable material on the site and mixing it into subsoil backfill wastes it. And spoil is not always suitable backfill: expansive clays and organic material do not compact usefully against a foundation, and using them there is how basement walls end up loaded in ways nobody designed for.

Before you dig: 811

Call 811. Every state, free, legally required, a few business days’ notice.

Locators come out and mark public utilities in the dig area with paint and flags. This does not cover private lines — the run to a detached garage, an irrigation main, a propane line, an invisible fence — so those are yours to know about.

The asymmetry here is extreme. The call costs nothing. A struck gas line is life-threatening and a struck fibre trunk can produce a five-figure bill within minutes. There is no version of this where skipping the call is the right decision.

Trench safety, briefly and seriously

Once a trench is roughly five feet deep, OSHA requires a protective system — sloping the walls back, benching them, or using a trench box. Soil weighs around 3,000 pounds per cubic yard, a collapse gives no warning, and a person buried to the chest cannot self-extract and often cannot breathe.

Trench collapses kill people every year in the US, almost always in excavations that “were only going to be open for an hour.” Depth is not the only factor — soil type, adjacent loads, vibration and water all matter — but five feet is the line where the rules become explicit.

What this leaves out

• Over-dig and working room. A foundation hole is dug larger than the foundation so people can work outside the forms. Add it to your dimensions.
• Slope and benching. Sloped walls add substantial volume on a deep excavation, and are not captured by a rectangular calculation.
• Rock, water and unsuitable material. The three things that turn an excavation quote into a change order.
• Equipment mobilisation. Usually a fixed line item, often significant on small jobs.
• Permits, erosion control and site restoration.
• Compaction of backfill. Placed in lifts, tested where it matters.

Downstream of the hole: the french drain calculator covers the trench that keeps the water away from it, and the gravel calculator handles the stone going back in.