Excavation Calculator (with Swell Factor)
Calculate cubic yards of dirt to be removed during excavation — in-place volume, loose/hauled volume (with swell factor), and truck-load count for proper job planning.
Excavation Calculator
Enter project dimensions below — results update instantly. Switch units freely.
Estimates assume typical industry density and waste factors. Always verify with your supplier and local building code before purchasing material.
Why ‘Dirt Expands’ When You Dig It Up
Undisturbed soil in the ground is tightly packed. Dig it up with an excavator bucket and it expands 20-45% depending on soil type. The loose excavated volume is always bigger than the hole it came out of.
Soil swell factors (approximate):
- Topsoil: 15-25% swell
- Sandy soil: 10-15% swell
- Common clay: 25-35% swell
- Heavy clay: 30-40% swell
- Rocky / shale: 35-50% swell
- Solid rock (blasted): 50-70% swell
Why this matters:
- Hauling trucks are sized by loose volume — a 12-yd³ truck holds 12 loose cubic yards, not 12 in-place yards.
- Disposal fees are charged by loose volume — you pay for swollen dirt.
- Storage areas need to fit loose volume — not in-place volume.
This calculator outputs both values: in-place volume (hole size) and loose volume (what you haul or pile).
Excavation Volume Formulas
Loose yd³ = In-place yd³ × (1 + Swell %)
Truck Loads = Loose yd³ ÷ Truck Capacity
Typical dump truck capacities (loose volume):
- 10-wheeler single-axle: 10-12 yd³
- Tri-axle: 14-18 yd³
- Dump trailer (articulated): 20-30 yd³
Also account for:
- Over-excavation — excavator commonly cuts 3-6 inches deeper than planned on soft spots. Add 5-10% to volume.
- Ramp for equipment — temporary ramp in/out of excavation adds its own dirt
- Banking — some excavators leave 1-2 ft perimeter shelf for stability
| Soil Type | Swell % | Multiplier | 1 In-place yd³ = |
|---|---|---|---|
| Topsoil / loam | 15-25% | 1.15-1.25 | 1.2 loose yd³ |
| Sandy soil | 10-15% | 1.10-1.15 | 1.13 loose yd³ |
| Sand & gravel mix | 15-20% | 1.15-1.20 | 1.18 loose yd³ |
| Common clay | 25-35% | 1.25-1.35 | 1.30 loose yd³ |
| Heavy / wet clay | 30-40% | 1.30-1.40 | 1.35 loose yd³ |
| Decomposed granite | 25-35% | 1.25-1.35 | 1.30 loose yd³ |
| Shale / weathered rock | 35-50% | 1.35-1.50 | 1.42 loose yd³ |
| Blasted rock | 50-70% | 1.50-1.70 | 1.60 loose yd³ |
| Frozen soil (if excavated) | 30-50% | 1.30-1.50 | 1.40 loose yd³ |
Swell factors are approximate. Moisture content and compaction state vary. Order on the high side of the range to avoid shortage.
| Project | Dimensions | In-place yd³ | Loose yd³ (avg 25% swell) |
|---|---|---|---|
| Deck pier footing | 1 × 1 × 4 ft | 0.15 | 0.19 |
| Foundation footing (100 lf) | 100 × 2 × 2 ft | 14.8 | 18.5 |
| Crawl space (30×40 ft × 4 ft) | 30 × 40 × 4 ft | 177.8 | 222 |
| Full basement (30×40 ft × 8 ft) | 30 × 40 × 8 ft | 355.6 | 444 |
| Pool excavation (16 × 32 × 8 ft) | 16 × 32 × 8 ft | 151.7 | 190 |
| Utility trench (100 × 2 × 3 ft) | 100 × 2 × 3 ft | 22.2 | 28 |
| Septic field (60 × 80 × 4 ft) | 60 × 80 × 4 ft | 711 | 889 |
| Driveway cut (60 × 12 × 1 ft) | 60 × 12 × 1 ft | 26.7 | 33.3 |
Add 10-15% for over-excavation and equipment access ramps. Verify with a soils engineer for anything beyond simple residential.
Real-World Example Calculations
Basement Excavation 30 × 40 × 8 ft
Full basement excavation for new single-family home.
- Length × Width
- 40 × 30 ft
- Depth
- 8 ft
- Soil type
- Clay (30% swell)
Takeaway: Multi-day operation. Budget 3-5 days for excavation and haul-off. Include cost for haul-off ($150-300/load at 2026 rates).
Pool Excavation 16 × 32 × 8 ft
In-ground pool dig, average 8 ft depth (deep end to shallow).
- Length × Width
- 32 × 16 ft
- Avg depth
- 8 ft
- Soil type
- Sandy loam (20% swell)
Takeaway: 1-2 days excavation. Keep some soil on-site for eventual backfill; haul off the rest.
Foundation Trench Footings 100 lf
Continuous footing excavation for 100 linear feet of foundation, 24-in wide × 30-in deep.
- Length
- 100 ft
- Width
- 2 ft
- Depth
- 30 in (2.5 ft)
- Soil type
- Sandy (15% swell)
Takeaway: 1-day job for a medium excavator. Minimal haul-off; most soil gets backfilled against foundation after pour.
Frequently Asked Questions
How do I calculate excavation volume?
Multiply length × width × depth (in feet), divide by 27 for cubic yards. Then multiply by (1 + swell factor) for loose volume. Example: 30 × 40 × 8 ft = 356 in-place yd³ × 1.25 = 445 loose yd³.
What is soil swell factor?
The percentage increase in volume when soil is excavated. Undisturbed soil is compressed; digging it loosens the particles. Swell factors range from 10% (sand) to 70% (blasted rock). Average residential: 20-30%.
How much does excavation cost?
In 2026: $10-25 per in-place cubic yard (basic residential). Rocky soil adds $10-25/yd³; haul-off disposal adds $15-40/yd³. Full basement excavation: $3,500-8,500. Pool excavation: $1,500-3,500.
How many cubic yards per dump truck?
Standard single-axle dump: 10-12 loose cubic yards. Tri-axle: 14-18 yd³. Dump trailer: 20-30 yd³. Always confirm truck size with your excavator before calculating loads.
Do I need to haul away excavated dirt?
Depends on what will be done with it. Foundation excavation: most soil stays on-site for backfill after foundation is built. Pool excavation: typically hauled off. Grading: depends on site balance (cut vs. fill). Always confirm disposal plan before excavation starts.
What's the difference between bank, loose, and compacted volume?
Bank volume: undisturbed in-ground volume (the hole). Loose volume: after excavation, swollen by 10-70%. Compacted volume: after placement and compaction, typically 0-10% more than bank. When ordering fill material, specify which volume you mean — they're significantly different.
Do I need a permit for excavation?
Most jurisdictions require permits for foundation excavations, pool excavations, fills over 50 yd³, and any excavation over 5 ft deep. OSHA also requires safety protocols (sloping, shoring, protective systems) for excavations over 5 ft deep. Always check local code and call 811 before digging for utility locates.