Excavation Calculator
Calculate the bank cubic yards to dig, the loose volume after swell, the weight in tons, how many truckloads it takes to haul away, and the haul-off cost.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Bank volume (in place)
- 66.67 cu yd
- 30 ft x 20 ft x 3 ft of undisturbed soil
- Loose volume to haul
- 83.33 cu yd
- Bank volume plus 25% swell for loam or topsoil
- Weight
- 93.3 tons
- At 1.4 tons per bank cubic yard
- Truckloads
- 9 loads
- 83.3 cu yd loose / 10 cu yd per truck, rounded up
Excavation formula
Bank cu yd = Length (ft) x Width (ft) x Depth (ft) / 27
Loose cu yd = Bank cu yd x (1 + swell %) (sand 12%, loam 25%, clay 35%, rock 50%)
Tons = Bank cu yd x density (sand 1.5, loam 1.4, clay 1.5, rock 2.0 tons per bank cu yd)
Truckloads = Loose cu yd / truck capacity, rounded upWorked example
A 40 x 25 ft basement dug 8 ft deep in clay, hauled in 14 yard tri-axles at $15 per loose yard: bank volume is 40 x 25 x 8 = 8,000 cubic feet, or 8,000 / 27 = 296.3 cubic yards. Clay swells 35%, so the loose volume is 296.3 x 1.35 = 400 cubic yards. Weight is 296.3 x 1.5 = 444.4 tons.
Truckloads: 400 / 14 = 28.6, so 29 loads. Haul-off cost is 400 x $15 = $6,000 before disposal fees. At 8 ft deep the walls must be sloped back or shored, which adds excavation volume beyond the footprint.
Quick reference
| Soil | Swell | Loose cu yd | Tons | 10 cu yd loads | 14 cu yd loads |
|---|---|---|---|---|---|
| Sand and gravel | 12% | 112 | 150 | 12 | 8 |
| Loam or topsoil | 25% | 125 | 140 | 13 | 9 |
| Clay | 35% | 135 | 150 | 14 | 10 |
| Rock, blasted | 50% | 150 | 200 | 15 | 11 |
Bank, loose and compacted volume
Excavators quote digging by the bank cubic yard, the volume measured in the ground before it is disturbed. Once the bucket breaks it loose, air gets between the particles and the pile grows: sand and gravel by roughly 12 percent, loam by 25, clay by 35, and blasted rock by half again. Trucking and dump fees are charged on that loose volume, which is why a 67 yard hole produces 83 yards of loads.
If the soil is coming back as fill, the third number matters: compacted volume. Loam placed and compacted in lifts ends up about 10 percent smaller than it was in the bank, so a hole backfilled with its own spoil comes up short. Order extra fill or plan on the difference.
Before and during the dig
Call 811 or file the locate online two to three business days ahead (each state sets the notice); the marks are free and the ticket expires in 10 to 30 days. Locators stop at the meter, so the gas line to a pool heater, irrigation, the well line and the septic lateral need a private locate, typically $200 to $500. Inside the tolerance zone, 18 to 24 in either side of a mark depending on the state, the digging is by hand or vacuum. Most counties want a grading permit above about 50 cubic yards of cut or fill and silt fence downhill of the pile. The spoil goes 2 ft back from the edge (OSHA 1926.651(j)(2)), off the septic field and on your side of the line.
Any excavation 5 ft or deeper falls under OSHA 1926.652. The walls are sloped back at 1-1/2:1 for Type C soil (1:1 for Type B, 3/4:1 for Type A), benched, or supported with a trench box or shoring. A ladder goes within 25 ft of every worker once the trench passes 4 ft (1926.651), and a competent person inspects it daily and after every rain. Sloping widens the top and adds volume, often 50 to 100 percent on an 8 ft basement in Type B or C soil. Rates in 2026 typically run $150 to $250 per hour for a 20 ton excavator with operator and $90 to $130 per hour per dump truck. A 3 to 4 ton mini you run yourself is $300 to $450 a day plus $100 to $200 delivery each way, and a trench box $100 to $200 a day.
What this calculator leaves out
The extra volume from sloped walls and the working room outside the footings, 2 to 3 ft each side for forms and waterproofing. Rock or hardpan that changes the machine and the price, dewatering, and topsoil stripped and stockpiled separately. Backfill and compaction in 8 to 12 in lifts, the stone under footings and slabs, silt fence and the grading permit. Dump or clean-fill fees on top of hauling, typically $5 to $25 per yard at a fill site and more at a landfill, and the private locate. A mixed load with roots, concrete or asphalt in it gets rejected at a clean-fill site or billed as demolition debris.
Mistakes that cost money
- Digging inside the 811 tolerance zone: hand dig within 18 to 24 in of the marks, or the gas or fiber repair is yours.
- 811 stops at the meter: the pool heater gas line, irrigation, well line and septic lateral need a private locator, typically $200 to $500.
- Spoil piled at the edge: OSHA 1926.651(j)(2) wants it 2 ft back, and the surcharge is what caves the wall in on the crew.
- No box or slope at 5 ft: OSHA 1926.652 requires one, plus a ladder within 25 ft of every worker from 4 ft down.
- A 1.7 ton mini on a basement: it reaches 7 ft and moves under 10 bank yards an hour, so 300 yards takes a week.
- Booking trucks by bank yards: haulers bill loose yards, 25 percent more for loam, and a tandem legally carries about 13 tons.
Key facts
- Soil has three volumes: bank (undisturbed in the ground), loose (after digging, 12 to 50 percent larger), and compacted (after placement, often smaller than bank).
- Loam swells about 25 percent when excavated, so 100 bank cubic yards becomes 125 loose yards in the trucks.
- Call 811 at least two to three business days before digging; utilities mark their lines for free and it is the law in every state.
- OSHA requires a protective system (sloping, benching, shielding or shoring) for any trench 5 ft or deeper, and an engineered design at 20 ft or deeper.
- A tandem dump truck carries about 10 cubic yards, a tri-axle 14 to 16, and a semi end dump 18 to 22, limited by weight as much as volume.
Frequently asked questions
How do I calculate excavation in cubic yards?
Multiply length, width and depth in feet and divide by 27. A 30 x 20 ft area dug 3 ft deep is 1,800 cubic feet, or 66.67 cubic yards in the bank.
How much does it cost to dig and haul a basement?
In 2026, typically $150 to $250 per hour for a 20 ton excavator with operator and $90 to $130 per hour per dump truck. Hauling and dump fees add $10 to $30 per loose yard. The 296 bank yard basement in the example is 400 loose yards, about 29 tri-axle loads and two to three machine days. Figure $10,000 to $20,000 before rock, dewatering, the sloping volume and backfill. Trucking is billed on loose yards, 25 to 35 percent more than the hole.
How many truckloads is 100 cubic yards of dirt?
About 13 loads of loam in a 10 yard tandem, because 100 bank yards swells to 125 loose yards. A 14 yard tri-axle takes it in 9 loads.
How deep can you dig before you need shoring?
OSHA requires sloping, benching, a trench box or shoring at 5 ft deep, and an engineer-designed system at 20 ft. Many contractors protect anything over 4 ft in unstable soil.
Sources and references
- 29 CFR 1926.652, Requirements for protective systems (OSHA)
- Trenching and Excavation overview (OSHA)
- 811 Before You Dig (Common Ground Alliance)
- NIST Handbook 44, Appendix C, General Tables of Units of Measurement (NIST)
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