Excavation Calculator
Calculate excavation volume in cubic yards from length, width, and depth, plus the loose (swelled) volume to haul away and an approximate weight in tons.
Como usar esta calculadora
- 1Enter the length and width of the area to excavate.
- 2Enter the depth, in feet or inches.
- 3Set the soil swell factor for hauling (about 25% for average soil).
- 4Read the bank volume to dig and the loose volume to haul away.
Como funciona
Excavation volume
volume (ft³) = length × width × depth (all in feet) cubic yards = cubic feet ÷ 27 loose volume = bank volume × (1 + swell factor) swell ≈ 25% average soil, up to ~40% for clay
Excavation volume is a straightforward box calculation — length times width times depth — but with two twists that trip people up. The first is units: excavation is quoted in cubic yards, while dimensions are usually measured in feet, and there are 27 cubic feet in a cubic yard (three feet in each direction), so the cubic-foot figure must be divided by 27. The second, more important twist is soil swell. Soil in the ground is compacted, but the moment it is dug up it breaks into clumps with air gaps and expands, so the loose pile you have to load and haul away occupies noticeably more space than the hole it came from. This swell is typically around 25% for average soil and higher for clay. The bank volume — the compacted in-ground amount — determines the size of the excavation and any backfill needed, while the loose volume determines how much material you must transport, which is why both figures are calculated separately.
Exemplo resolvido
Digging a 20 ft by 10 ft area to a depth of 1 foot is 20 × 10 × 1 = 200 cubic feet, or 200 ÷ 27 ≈ 7.4 cubic yards in the ground. Once dug, at 25% swell that becomes about 9.3 loose cubic yards to haul away — one trip for a 10-yard dump truck.
Excavation Calculator: o guia completo
Bank volume versus loose volume
The single most important concept in excavation estimating is the difference between bank volume and loose volume, and getting it wrong leads to under-ordered trucks and blown schedules. Bank volume, sometimes called in-situ or in-place volume, is the amount of soil sitting compacted in the ground — it is what you calculate directly from the dimensions of the hole, and it determines how big the excavation is and how much backfill you would need to refill it. Loose volume is the same soil after it has been dug up, broken apart, and piled or loaded, and it is always larger.
The reason for the expansion is that undisturbed soil is packed tight, with mineral particles pressed together over long periods. Excavating shatters this structure into clods and fragments that trap air between them, increasing the total volume even though the mass of soil is unchanged. This phenomenon, called swell or bulking, means a hole that measures ten cubic yards will produce noticeably more than ten cubic yards of loose material to cart away. Hauling contracts and truck counts must be based on the loose volume, while the dig itself and any refilling use the bank volume — mixing the two is a classic estimating error.
How much soil swells, and why it varies
The amount soil swells when excavated depends heavily on its type. Loose, granular materials like sand swell relatively little, often around 10 to 15%, because their particles are already fairly loosely arranged in the ground. Average topsoil and loam swell around 25%, a reasonable default for mixed soils. Clay swells the most, sometimes 35 to 40% or more, because its fine, tightly bound particles form large clumps with substantial voids when broken up. Rock, once blasted or ripped, can swell 50% or beyond.
This variability matters when ordering removal. Using a flat swell factor without regard to the soil can leave you short of hauling capacity for a clay site or over-ordering for sandy ground. It is worth identifying the dominant soil type before settling on a figure. There is also a related concept, shrinkage, that applies in reverse: when loose soil is placed and compacted as fill, it takes up less space than its loose volume, so the amount of loose material needed to fill a given space is more than the space's bank volume. Excavation and filling are two sides of the same swell-and-compact relationship, and professional earthwork estimates track both.
From volume to trucks, weight, and cost
Once you know the loose volume, the practical questions are how many truckloads it takes to remove and roughly what it weighs, both of which drive cost. Dump trucks are rated by capacity in cubic yards — a common size carries around 10 to 12 cubic yards — so dividing the loose volume by the truck capacity and rounding up gives the number of trips, each of which has a cost in fuel, time, and disposal fees. For a large excavation this quickly becomes the dominant expense, which is why an accurate loose-volume figure directly protects the budget.
Weight matters too, because trucks and equipment have load limits and disposal sites often charge by the ton. Soil is heavy: a bank cubic yard of average moist soil weighs well over a ton, so even a modest excavation moves many tons of material. The weight also depends on soil type and moisture — wet clay is far heavier than dry sand — so weight estimates are approximate. Still, knowing the ballpark tonnage helps size equipment, check that trucks are not overloaded, and anticipate disposal charges. The volume this calculator provides is the starting point; translating it into trucks, weight, and ultimately cost is what turns a measurement into a plan.
Perguntas frequentes
How do I calculate cubic yards of dirt?
Multiply length × width × depth in feet to get cubic feet, then divide by 27 (the cubic feet in a cubic yard). A 20 × 10 ft area dug 1 foot deep is 200 cubic feet, or about 7.4 cubic yards in the ground.
Why is there more dirt to haul than the hole's volume?
Because soil swells when dug. Compacted in-ground soil breaks into clumps with air gaps when excavated, expanding its volume — about 25% for average soil, up to 40% for clay. So the loose pile to haul away is larger than the hole. Order hauling by the loose volume.
How much does excavated soil weigh?
A lot — roughly 1.3 to 1.5 tons per bank cubic yard for average moist soil, more for wet clay and less for dry sand. Even a small excavation moves many tons. Weight varies with soil type and moisture, so treat estimates as approximate for sizing trucks and disposal.
What swell factor should I use?
About 25% for average soil and loam, 10–15% for sand, and 35–40% or more for clay and rock. It depends on the soil type, so identify the dominant material before choosing. Using the wrong factor can leave you short of hauling capacity or over-ordering trucks.