Excavation Calculator
GroundworkMeasurements in, purchasing amount out
How the Excavation Calculator works
The calculator finds the bank volume of the cut — the ground as it sits before you dig — and weighs it with the selected soil’s bulk-density range. It then adds that soil’s swell to give the loose volume that actually leaves the site, and counts dump truck loads off the loose figure. The extra percentage is working room: over-dig for forms, footings, or drainage stone. Set it to 0 for the bare hole.
Using your measurements
12 ft × 8 ft × (12 in ÷ 12) ÷ 27 = 3.56 cu yd
Density assumption: Topsoil / loam · 2,000–2,400 lb/yd³
The full breakdown
How to calculate excavation volume — bank yards, soil swell factor, loose haulage & truck loads
The excavation calculator above turns the dimensions of a cut into bank cubic yards, loose cubic yards, tons, and dump truck loads. It covers a footing, a drainage or utility trench, a basement, an in-ground pool, or a pond, and the figures guard against the same two surprises every time: too few trucks booked, and a disposal bill that grows once the spoil is loose. Once the footing is dug, the concrete calculator sizes the pour.
In civil engineering and earthmoving, soil is measured in three distinct volume states: Bank Cubic Yards (BCY), Loose Cubic Yards (LCY), and Compacted Cubic Yards (CCY). Bank volume represents earth in its natural, undisturbed in-situ state in the ground. Once an excavator or backhoe bucket digs into the ground, cohesive soil bonds break apart and air fills the interstitial voids. This physical expansion is known as the "swell factor", causing excavated soil to expand by 15% to 30% for standard loams, 20% to 40% for heavy clays, and up to 50% to 65% for blasted or ripped rock.
Hole dimensions alone undercount the haulage. An in-ground pool dug 20 × 40 ft and 6 ft deep is 177.8 bank cubic yards of undisturbed earth. With a 25% swell in loam, the spoil pile grows to 222.2 loose cubic yards. A tandem dump truck carries roughly 10 to 14 loose cubic yards, so hauling it away takes 16 to 23 truckloads — not the 13 to 18 the bank figure would suggest. The truck count above is worked from the loose figure for exactly that reason.
For a trench or pit with sloped walls — the sloping and benching OSHA requires in deeper cuts — enter the average of the top and bottom widths. That is exact for a trench with evenly sloped sides, and close for a pit sloped on all four. Sloping adds a lot of spoil: a 5 ft deep trench cut back at 1:1 on both sides is 10 ft wider at the top than at the bottom, and that wedge of soil is hauled like the rest.
Soil type, swell factor & bulk density reference table
Excavated soil expands significantly upon disturbance. Bank density reflects in-place compaction, while loose density and swell factor determine hauling tonnage and truck loads.
| Excavation | Weight | Swell when dug |
|---|---|---|
| Sand & gravel | 2,400–2,900 lb/yd³ | +15% |
| Clay | 2,600–3,000 lb/yd³ | +35% |
| Mixed soil & rubble | 2,300–2,800 lb/yd³ | +30% |
| Broken rock | 3,000–3,800 lb/yd³ | +60% |
Recommended excavation depth & slope standards by project
Standard excavation depths, trench slope ratios (angle of repose), and safety benching guidelines across common residential and commercial earthwork projects.
| Shallow footings & slab edge turn-downs | 12–24 in (30–60 cm) |
|---|---|
| Frost-protected strip footings & stem walls | 36–48 in (90–120 cm, below local frost line) |
| Water, sewer & utility trenching | 4–6 ft (1.2–1.8 m, OSHA protection required at 5 ft) |
| Residential in-ground swimming pools | 3–8 ft (0.9–2.4 m + 1 ft over-dig for gravel/plumbing) |
| Full residential basements & walkouts | 8–10 ft (2.4–3.0 m with perimeter over-dig) |
| Agricultural ponds & retention basins | 6–15 ft (1.8–4.5 m with 3:1 safety side slopes) |
Hauling calculations: loose yards, tons & dump truck loads
A standard tandem dump truck carries 10–14 loose cubic yards (~15–20 tons), while a tri-axle truck carries 14–18 loose cubic yards (~20–25 tons), and a semi end-dump carries 20–26 loose cubic yards (~28–32 tons). Always divide loose cubic yards by truck volume capacity, and verify maximum road axle weight limits before dispatching haulers.
One cubic yard of undisturbed bank soil weighs approximately 2,000 to 2,800 lb (1.0 to 1.4 tons), yielding 1.15 to 1.4 loose yards in the truck.
Crucial excavation mistakes and safety hazards to avoid
Ignoring soil swell when ordering dumpsters and haul trucks
Ordering haulage based strictly on bank cubic yards leaves 20% to 40% of the loose dirt trapped on site once the dumpsters are full. Always calculate disposal and trucking using loose cubic yards adjusted for your soil type.
Surcharging the trench edge with heavy spoil piles
Placing excavated dirt, heavy equipment, or loaded dump trucks right next to the trench lip exerts intense lateral surcharge pressure. OSHA requires all spoil piles and machinery to stay at least 2 feet (0.6 m) back from the excavation edge to prevent catastrophic cave-ins.
Digging without calling 811 for utility locates
Striking underground natural gas, electrical lines, water mains, or fiber-optic cables causes severe injury, catastrophic explosions, and massive liability fines. Always call 811 (or local utility mark-out services) at least 48 to 72 hours before breaking ground.
Entering trenches deeper than 5 feet without cave-in protection
One cubic yard of dirt weighs as much as an automobile (~2,700 lb). Soil collapses happen without warning. Any trench 5 feet (1.5 m) deep or greater requires an OSHA-compliant protective system: sloping, benching, aluminum hydraulic shoring, or a steel trench box.
Frequently Asked Questions
Excavation calculations, soil swell, equipment & safety rules
Why is the loose volume bigger than the hole?
Digging breaks the soil apart and lets air into it, so the same material takes up more room in a truck than it did in the ground. That growth is the swell factor: roughly 10–20% for sand and gravel, 20–30% for loam, 30–40% for clay, and 50% or more for blasted rock. Trucks, dumpsters, and spoil piles are all sized on the loose figure.
Does swell change the weight?
No. Swell adds air, not soil, so the tons are the same in the ground as in the truck. That is why the weight row works from the bank volume. With ordinary soil a truck usually fills by volume before it reaches its weight limit; with wet clay or rock, check both.
How do I measure a trench or pit with sloped sides?
Enter the average width: the top width plus the bottom width, divided by two. For a trench with evenly sloped walls, that gives the exact volume. For a pit sloped on all four sides, average the length the same way; the result is close, and slightly under for deep, steep cuts.
What is excavation?
Excavation is the process of moving earth, rock, and other materials with heavy machinery (such as excavators, backhoes, and bulldozers) or hand tools to create an open cavity, trench, foundation pit, or grade cut. It is the initial site preparation phase for building foundations, roads, utilities, swimming pools, basements, and drainage systems.
What is shoring in excavation?
Shoring is a temporary structural support system installed inside an excavation or trench to prevent soil collapse and trench wall cave-ins. Common shoring methods include hydraulic aluminum pistons with timber or steel sheeting, pneumatic shores, soldier piles with lagging, and trench shields (trench boxes) that protect workers working inside the trench.
What is the soil removed from an excavation called?
The soil removed during an excavation is officially termed "spoil" or "excavated spoil". When piled on the ground next to the cut, it is called a "spoil pile". Because disturbed soil expands in volume, the spoil is measured in loose cubic yards (LCY) rather than bank cubic yards (BCY).
How much does excavation cost?
Residential excavation generally costs between $50 and $200 per cubic yard, or $1,500 to $6,000 for small foundation/grading projects and $8,000 to $25,000+ for full basements and large swimming pools. Costs depend on soil type, rocky or wet terrain, equipment access, haul distance, and dump site disposal fees.
What is benching in excavation?
Benching is an earthwork slope-protection method where the sides of an excavation are formed into one or a series of horizontal steps or terraces with near-vertical cuts between them. OSHA permits benching in cohesive soils (Type A and Type B), but strictly prohibits benching in loose, granular Type C soils.
Where is the typical point of failure in an excavation?
The typical point of failure in an excavation occurs along a diagonal shear plane originating at the lower third or toe of the trench wall (base failure or rotational slip), or at the upper lip caused by tension cracking and surcharge loads (such as spoil piles or heavy machinery positioned too close to the edge).
What are the three types of excavation?
In engineering classification, the three primary types of excavation by material are: 1) Topsoil / Surface Excavation (clearing organic surface layers), 2) Earth Excavation (removing subsoil, clay, and gravel below topsoil), and 3) Rock Excavation (clearing solid ledge or bedrock requiring blasting, hydraulic hammering, or ripping). By construction geometry, excavations are also categorized as Open Excavation, Trenching, and Pit/Shaft Excavation.
What is the 4 foot rule in excavation?
Under OSHA standard 29 CFR 1926.651(c)(2), any trench or excavation 4 feet (1.22 m) deep or greater must provide an accessible means of egress — such as a stairway, ramp, or secured ladder — requiring no more than 25 feet of lateral travel for any worker. Trenches 4+ feet deep in potential hazard areas also require atmospheric testing for oxygen deficiency and toxic gases.
What is the difference between a trench and an excavation?
An excavation is any man-made cut, cavity, trench, or depression formed by earth removal. A trench is a specific sub-category of excavation: a narrow cut where the depth is greater than the width, and the width at the bottom does not exceed 15 feet (4.57 m). In short, all trenches are excavations, but not all excavations are trenches.