ClutchCalcs

Construction

Excavation Volume Calculator

Digging a foundation, basement, swimming pool, drainage trench, or just a big landscaping cut — you need to know two numbers before you call the dump truck: in-place volume (how much dirt is in the hole) and loose volume (how much you actually haul away, because dirt expands 20-35% when you dig it up). This calculator runs the math for any rectangular excavation, applies a realistic swell factor based on soil type, and tells you how many standard 10-cubic-yard dump truck loads it'll take to get rid of the spoil. Useful for budgeting trucking, sizing dumpsters, and figuring out how much fill you need to bring back in.

Enter dimensions to begin.

Swell factor by soil type

When you excavate, the soil loosens and takes up more volume than it did in the ground. Industry swell factors:

  • Sand: 10-15%
  • Sandy loam: 15-20%
  • Common loam (the default): 20%
  • Clay: 25-30%
  • Hard pan / dense clay: 30-35%
  • Rocky soil / fractured rock: 35-50%
  • Solid rock blasted: 50-70%

Worked example: 20 ft × 15 ft × 3 ft basement footprint = 900 cu ft = 33.3 cu yd in-place. At 20% swell = 40 cu yd loose. At 10 cu yd per dump truck = 4 truckloads.

Truck capacities (for hauling estimates)

  • Pickup truck (half-ton bed): ~1 cu yd loose (or 1.5 cu yd if mounded). Useful for tiny jobs.
  • 3/4-ton dump trailer: 3-5 cu yd
  • Tandem dump truck: 8-10 cu yd
  • Tri-axle dump truck: 10-15 cu yd (the standard residential excavation truck)
  • End-dump trailer: 20-25 cu yd (used for commercial excavation)
  • Roll-off dumpster: 10, 20, 30, or 40 cu yd containers — useful when truck access is limited

How to use this calculator

  1. Length, width, depth in feet — all sides of the excavation.
  2. Swell factor: 20% for common loam, 25-30% for clay, 35% for rocky.
  3. Output: loose volume (what you haul), in-place volume (what you dig), cubic feet, and number of 10-cubic-yard truck loads.
  4. For sloped or irregular excavations, break into rectangles or compute average depth.
  5. Plan for over-excavation at edges (typical foundations dig 1-2 ft wider than the footprint for working room).

Common scenarios

Basement excavation, 30 ft x 40 ft x 9 ft deep (for full basement plus 1 ft over-dig). 10,800 cu ft = 400 cu yd in-place. At 20% swell = 480 cu yd loose. 48 tri-axle truck loads. Multi-day excavation operation; plan $7,000-15,000 for trucking and disposal alone.

Swimming pool excavation, 16 ft x 32 ft x 5 ft average depth. 2,560 cu ft = 95 cu yd in-place. At 20% swell = 114 cu yd loose. 11-12 truck loads. About $2,500-4,500 in trucking on a typical pool project.

Drainage trench, 2 ft wide x 100 ft long x 4 ft deep. 800 cu ft = 30 cu yd in-place. At 25% swell (heavy clay common in drain projects) = 37 cu yd. 4 truckloads, or keep the spoil on-site if you have room.

FAQ

Why is loose volume different from in-place volume? +
When you dig soil out of the ground, the particles separate slightly and trap air — the loose pile takes more space than the compact in-ground volume. Truck hauling and dumpster volumes are measured loose. When you backfill and compact, the material returns to roughly in-place volume.
How do I figure out my soil type? +
Dig a small test hole. Sand: grainy, drains quickly, doesn't hold together. Loam: dark, crumbly, holds together when squeezed but breaks apart easily. Clay: smooth, sticky when wet, holds shape like clay. Rocky: includes visible rocks or cobbles. For commercial sites, get a geotechnical report — it identifies soil type and recommends fill specifications.
How much does dirt cost to haul? +
Trucking + disposal in 2025: $50-150 per truck load (10 cu yd), depending on distance to disposal site, fuel cost, and dump fees. For clean fill, you may get free disposal or even paid pickup if a construction project nearby needs fill. Contaminated soil (urban sites, industrial areas) can cost $300-600 per truck load.
How deep is one truck load on the ground? +
Spread out and graded flat: 10 cu yd over 1,000 sq ft = 0.3 ft (3.6 inches) of fill. Useful for grade-fill estimates: a yard needing 6 inches of fill over 800 sq ft = ~15 cu yd of compacted fill, or ~18 cu yd loose-delivered.
Can I keep the spoil on site instead of hauling? +
Yes, if you have room and any grade you can level the fill into. Many residential projects can absorb 20-100 cu yd of excavated soil onsite as fill for grade improvements, planting beds, or burying construction debris. For larger excavations (basement digs), hauling is usually faster.
What does "compacted" mean in fill specifications? +
When you backfill with imported soil or stone, you compact it in lifts (6-12 inches at a time) using a vibrating plate or jumping jack tamper. Compacted volume is similar to in-place volume — sometimes slightly less if you can over-compact. Fill orders should specify compacted volume on the contract, not loose; you may need 20-30% more loose delivery to hit the compacted target.
How do I check excavation depth? +
Use a transit level, builder's level, or laser level set up at a reference benchmark. Run grades from the benchmark to the excavation. For permits and inspection, depth is usually measured from finished floor (basement) or grade (foundation footing).
What about hand digging vs machine? +
For volumes under 5 cu yd: hand digging is feasible (a 16-cu-ft pile is one wheelbarrow x 30 trips x 1 hour). Above 5-10 cu yd: rent a mini-excavator ($300-400/day) or compact loader. Above 50 cu yd: hire a full excavation contractor with proper equipment. Hand-digging anything close to a building or utility is hugely safer than machine excavation.