Calculate bank volume, loose volume, truckloads, spoil pile size and cost for trenches, foundations, pools, basements and site grading. Includes soil swell factors, shrinkage factors, OSHA safety checks and 2025 pricing.
- 6 Excavation Types
- Swell & Shrinkage
- Truckload Planning
- Spoil Pile Volume
- OSHA Safety Checks
- Full Cost Estimate
OSHA defines a trench as an excavation deeper than it is wide, no more than 15 ft wide. Trenches 5 ft or deeper require a protective system.
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Order summary
What Is Excavation?
Excavation is the removal of soil, rock or other material from the ground to create a cavity, trench or foundation bed. It is the first physical step of almost every construction project — from a residential footing to a full basement, a swimming pool, a utility trench or a site grading operation. The calculation is not simply length × width × depth, because soil expands when excavated and shrinks when compacted back into place. Getting the volume right is the difference between ordering one truckload and ordering three.
Bank volume
The volume of soil in its natural, undisturbed state. This is the volume you calculate from length × width × depth. It is what a surveyor measures and what an engineer designs against.
Loose volume
The volume of soil after excavation, when it is broken up and loaded into trucks. Soil swells by 15–80% depending on type. Loose volume is always larger than bank volume.
Compacted volume
The volume after soil is re-compacted as backfill or fill. Compacted volume is smaller than bank volume because compaction forces particles tighter than their natural state.
Why three volumes matter
You dig bank volume, haul loose volume and backfill compacted volume. Three different numbers. Using the wrong one leads to short loads, surplus spoil or under-compacted fill.
A cubic yard of clay in the ground does not become a cubic yard of clay in a truck. It becomes 1.2 to 1.4 cubic yards. If you order trucks based on bank volume and forget swell, the last load of spoil has nowhere to go. The calculator above applies the correct swell factor automatically based on soil type, and also computes the shrinkage factor if the spoil is coming back as compacted backfill.
Swell and Shrinkage Factor Reference
These are the standard industry swell and shrinkage factors by soil type. Swell increases the volume when soil is excavated. Shrinkage reduces it when soil is compacted back into place.
| Soil / material | Swell factor | Load factor | Shrink factor | Notes |
|---|---|---|---|---|
| Topsoil / loam | 15–25% | 0.80–0.87 | 10–15% | Light, easy to dig, low compaction |
| Sand, dry | 20–30% | 0.77–0.83 | 10–15% | Drains well, trenches need shoring |
| Sand, wet | 20–30% | 0.77–0.83 | 10–15% | Heavier, prone to collapse |
| Gravel, dry | 20–30% | 0.77–0.83 | 10–15% | Good bearing, low shrink |
| Gravel with clay | 30–50% | 0.67–0.77 | 15–25% | Sticky, requires more haul |
| Clay | 20–40% | 0.71–0.83 | 15–25% | Heavy, slow digging, high shrink |
| Clay, wet | 40% | 0.71 | 20–30% | Difficult, requires dewatering |
| Black cotton soil | 30–40% | 0.71–0.77 | 20–25% | Expansive, poor fill material |
| Rock, limestone | 40–80% | 0.55–0.71 | 0% | Requires blasting or breakers |
| Sandstone | 75–80% | 0.55 | 0% | Very hard, high swell |
Load factor = bank volume ÷ loose volume. It tells you how many bank cubic yards fit into one loose cubic yard. A load factor of 0.80 means one loose cubic yard contains 0.80 bank cubic yards of material. The lower the load factor, the more trucks you need.
How the Excavation Calculator Works
Six steps from dimensions to the order summary. The calculator handles the three different volumes and prints every conversion so you can check against the engineer's quantity sheet.
Bank volume
Length × width × depth in feet ÷ 27 gives bank cubic yards. This is the volume in the ground before digging.
Apply swell factor
Bank volume × (1 + swell %) = loose volume. This is what the trucks actually carry.
Truckloads
Loose volume ÷ truck capacity (cubic yards) = number of loads. Round up to whole trucks.
Apply shrink factor
If soil is reused as backfill, bank volume × (1 − shrink %) = compacted volume. This is what fits back in the hole.
Spoil to haul
Loose volume − (compacted volume back into hole × swell) = net spoil that leaves the site.
Cost estimate
Excavation cost (per yd³ bank) + hauling cost (per yd³ loose) = total project cost.
Worked Example — 60 ft trench, 2 ft wide, 4 ft deep in sand
| Step | Calculation | Result |
|---|---|---|
| Bank volume | 60 × 2 × 4 ÷ 27 | 17.78 yd³ |
| Swell factor (sand) | 25% | 1.25 multiplier |
| Loose volume | 17.78 × 1.25 | 22.22 yd³ |
| Truckloads (12 yd³) | ceil(22.22 ÷ 12) | 2 loads |
| Shrink factor (backfill) | 15% | 0.85 multiplier |
| Compacted backfill | 17.78 × 0.85 | 15.11 yd³ |
| Net spoil to haul | 22.22 − (15.11 × 1.25) | 3.33 yd³ |
| Excavation cost @ $75/yd³ | 17.78 × $75 | $1,333 |
| Hauling cost @ $25/yd³ | 3.33 × $25 | $83 |
| Total | — | $1,416 |
Notice the difference: 2 trucks show up to haul 22 cubic yards of loose soil, but only 3.3 cubic yards actually need to leave the site because the rest goes back as compacted backfill. Without the shrink factor, you would over-order hauling by a factor of seven.
Spoil Pile Volume and Footprint
Excavated soil that stays on site goes into a stockpile. The size of that stockpile determines whether you have room to work around it. A pile's volume depends on the shape and the soil's angle of repose — the natural slope angle the material forms when poured.
Conical pile
Volume = ⅓ × π × r² × h. Used when spoil is dumped from a single point. The angle of repose determines the relationship between radius and height.
Triangular windrow
Volume = ½ × base × height × length. Used when spoil is pushed into a long ridge alongside a trench. Common on utility projects.
Rectangular stockpile
Volume = length × width × height. Used when spoil is spread and leveled to fit a constrained area, such as a residential driveway.
Angle of repose
Sand: 30–35°. Gravel: 35–40°. Clay: 35–45°. Rock: 40–45°. The flatter the angle, the wider the footprint for the same volume.
Spoil storage matters for OSHA. Excavated soil must be kept at least 2 feet from the trench edge to prevent it from surcharging the wall and causing a collapse. If you have limited room, plan to haul spoil off-site rather than stockpile it close to the excavation.
OSHA Excavation Safety Requirements
Excavation and trenching are among the most hazardous construction operations. Cave-ins cause dozens of fatalities and hundreds of injuries every year. The OSHA standards (29 CFR 1926 Subpart P) apply to any excavation deeper than 4 feet and set specific requirements based on depth.
4 feet — egress required
Trenches 4 ft or deeper must have a ladder, stairway or ramp for exit. Workers cannot be more than 25 ft from an exit point. Test for atmospheric hazards in trenches 4 ft or deeper.
5 feet — protective system
Any trench 5 ft or deeper requires a protective system unless the entire excavation is in stable rock. Protective systems include sloping, benching, shoring or shielding.
20 feet — engineer required
Trenches 20 ft or deeper require a protective system designed by a registered professional engineer, or based on tabulated data approved by one. No exceptions.
Spoil setback
Excavated material, equipment and other surcharge loads must be kept at least 2 feet from the trench edge. This prevents the weight from pushing the trench wall inward.
Daily inspection
A competent person must inspect the excavation at the start of each shift and after every rainstorm or other event that could change conditions. No worker enters an uninspected trench.
Utility clearance
Know where underground utilities are located before digging. Call 811 (US) or your local utility locate service. Excavation work must protect, support or remove any exposed installations.
Excavation Cost Reference (2025)
Excavation pricing depends heavily on soil type, depth, site access and whether the spoil is hauled away. These are national averages for machine-dug residential and light commercial work.
| Soil condition | Cost per yd³ (bank) | Hauling per yd³ | Notes |
|---|---|---|---|
| Sandy soil | $40–$80 | $15–$50 | Fast digging, but trenches need shoring |
| Topsoil / loose fill | $50–$100 | $15–$50 | Most common residential type |
| Clay / compacted | $75–$150 | $15–$50 | Heavy equipment, slower production |
| Rocky soil | $100–$250 | $15–$50 | May need breakers or blasting |
| Rock (solid) | $150–$250+ | $25–$60 | Requires hydraulic breaker or blasting |
Cut-and-fill work (moving soil on-site to change grade) runs $1–$12 per cubic yard. Hauling dirt off-site runs $8–$25 per cubic yard depending on distance. A typical residential excavation job costs $1,659–$6,709, with an average of $3,979. Minimum job charges of $500–$1,500 are common — even a small trench can trigger a day-rate minimum.
Common Excavation Mistakes
Forgetting swell factor
Soil expands when excavated. A 20 cubic yard bank cut becomes 25 cubic yards loose. If you order trucks based on bank volume, you run short by 25%.
Ignoring shrink factor
Compacted backfill takes up less space than the original cut. If you assume 1:1 replacement, you either over-order or leave a surplus that has to be hauled anyway.
Not accounting for working room
Footings need 2–3 ft each side for formwork. Pools need 1–2 ft each side for gunite and plumbing. Basements need 2–3 ft each side. If you use the finished dimension, you dig too small.
No dewatering plan
Groundwater turns a simple dig into a pumping operation. Even a shallow water table requires dewatering before excavation. Cost adds $5–$25 per cubic yard depending on volume.
Storing spoil too close
OSHA requires spoil at least 2 ft from the trench edge. The weight of the spoil surcharges the wall and causes collapse. Even if it looks stable, the wall can give way without warning.
Skipping the utility locate
Striking a gas or electrical line during excavation can be fatal. Call 811 (US) or your local utility locate service before you dig. It is free and takes 2–3 business days.
Excavation safety is governed by OSHA 29 CFR 1926 Subpart P (Excavations) in the United States. Soil classification follows OSHA Appendix A to Subpart P (Type A, B and C). Swell and shrinkage factors are published in AASHTO M147 and standard earthwork references including the FHWA Earthwork Manual. Compaction testing uses AASHTO T180 (modified Proctor) and field density by ASTM D6938. UK and EU work follows BS 6031: Code of Practice for Earthworks.
Bank volume = (Length ft × Width ft × Depth ft) ÷ 27. Loose volume = Bank volume × (1 + Swell). Typical swell: sand 25%, clay 30–40%, rock 50–80%. Compacted volume = Bank volume × (1 − Shrink). Typical shrink: 10–25%. A 12 yd³ dump truck carries about 9–10 bank cubic yards after swell. Always add 10–15% waste on top for over-dig and spillage.
People Also Ask
How do I calculate excavation volume in cubic yards?
Multiply length × width × depth in feet, then divide by 27. That is the bank cubic yards — the volume in the ground before you dig. For a 60 ft trench, 2 ft wide, 4 ft deep: 60 × 2 × 4 = 480 ft³ ÷ 27 = 17.8 bank cubic yards. Then apply the swell factor to get loose volume for trucking.
What is the swell factor in excavation?
Swell factor is the percentage by which soil expands when excavated. When you dig soil from its natural state, it breaks into pieces with air pockets and takes up more volume. Typical swell factors: sand 20–30%, clay 20–40%, rock 40–80%. One cubic yard of clay becomes 1.2–1.4 cubic yards when dug. This is why you cannot use bank volume to order trucks.
What is the difference between bank volume and loose volume?
Bank volume is the soil in its natural, undisturbed state — what you calculate from dimensions. Loose volume is the soil after excavation, broken up and loaded into trucks. Loose volume is always larger than bank volume by the swell factor. You dig bank volume, you haul loose volume. The conversion is: Loose = Bank × (1 + Swell).
How many truckloads of dirt do I need?
Divide loose volume by the truck capacity. A standard dump truck carries 10–16 cubic yards loose. For 22 cubic yards of loose soil, a 12 yd³ truck needs 2 loads. Always round up. If only part of the spoil stays on-site as backfill, subtract the compacted backfill volume (re-expanded by swell) from the total loose volume first.
How much does excavation cost per cubic yard?
Excavation runs $40–$250 per cubic yard depending on soil type. Sandy soil: $40–$80. Topsoil: $50–$100. Clay: $75–$150. Rocky: $100–$250. Hauling adds $15–$50 per cubic yard if spoil leaves the site. A typical residential job costs $1,659–$6,709 with an average of $3,979.
How deep can I dig a trench without shoring?
OSHA requires a protective system for any trench 5 feet or deeper unless the entire excavation is in stable rock. Trenches 4 feet or deeper require a ladder, ramp or other means of egress within 25 feet of every worker. Trenches 20 feet or deeper require a protective system designed by a registered professional engineer. Never enter an unprotected trench deeper than 5 feet.
What is the shrinkage factor in earthwork?
Shrinkage factor is the percentage by which soil volume decreases when it is compacted back into place. Soil that is excavated and re-compacted is denser than its original natural state because compaction forces particles tighter together. Typical shrink factors: 10–15% for sand, 15–25% for clay, 20–25% for black cotton soil. Compacted = Bank × (1 − Shrink).
How do I calculate spoil pile volume?
It depends on the pile shape. Conical pile: V = ⅓ × π × r² × h. Triangular windrow: V = ½ × base × height × length. Rectangular stockpile: V = length × width × height. The pile volume equals the loose volume of spoil, not the bank volume. Remember OSHA requires spoil to be at least 2 feet from the trench edge.
What soil type is hardest to excavate?
Solid rock is the hardest, often requiring hydraulic breakers or blasting. It swells 40–80% and costs $150–$250+ per cubic yard. Wet clay is next — sticky, heavy and prone to wall collapse. It swells 40% and requires careful dewatering. Dry sand digs easily but trenches collapse without shoring. The easiest material is loose topsoil, which digs fast and swells only 15–25%.
How much working room do I need for formwork?
Add 2–3 feet on each side of the finished foundation for formwork, waterproofing and access. A footing that is 2 ft wide is typically excavated at 5–8 ft wide. A basement that is 30 ft wide is typically excavated at 35–36 ft. This is one of the most common estimating errors — using finished dimensions instead of excavated dimensions.
Do I need a permit to excavate?
Often yes. Permits are typically required for any excavation that: crosses a public right-of-way, changes drainage patterns, is over 4–5 ft deep near a structure, or is within a floodplain or protected zone. You also need to call 811 (or your local utility locate service) before digging anywhere. Fines for unpermitted excavation or utility strikes can reach $10,000+.
How fast can an excavator dig?
A hydraulic excavator typically moves 50–150 cubic yards per hour depending on size, soil type and site conditions. A small 1/4 cubic yard excavator might do 30 cubic yards per hour in tight conditions. A 2 cubic yard excavator in loose soil can hit 150 cubic yards per hour. Rock or wet clay cuts production by 50–70%. The hourly rate is $100–$250 including operator.
Can I use excavated soil for backfill?
Sometimes. Sand, gravel and sandy loam are good backfill — they compact well and drain. Clay and black cotton soil are poor backfill — they shrink and swell with moisture, causing settlement and cracks. Topsoil and organic material are never acceptable as structural backfill. Check the geotechnical report or ask the engineer before reusing excavated soil.
What is the angle of repose for soil?
The angle of repose is the steepest angle a soil pile can hold without sliding. Typical values: sand 30–35°, gravel 35–40°, clay 35–45°, rock 40–45°. A flatter angle means the spoil pile spreads wider for the same volume. If you have limited space, stockpiling is not practical — haul the spoil off-site.
Is this calculator free and does it store my data?
Yes and no. Every calculation runs entirely in your browser — nothing is sent to a server, nothing is stored. Your inputs are not saved anywhere. The only thing remembered is the rating counter, which uses your browser's local storage and never leaves your device.
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References
- OSHA 29 CFR 1926 Subpart P — Excavations. Occupational Safety and Health Administration.
- OSHA Appendix A to Subpart P — Soil Classification. Occupational Safety and Health Administration.
- Federal Highway Administration. Earthwork Manual — swell, shrink and load factor tables.
- AASHTO M147 — Standard Specification for Materials for Aggregate and Soil-Aggregate Subbase, Base, and Surface Courses.
- AASHTO T180 — Standard Method of Test for Moisture-Density Relations of Soils Using a 4.54-kg Rammer and a 457-mm Drop.
- ASTM D6938 — Standard Test Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods.
- British Standards Institution. BS 6031: Code of Practice for Earthworks.
Confirm soil classification, swell/shrink factors and protective system requirements with a geotechnical engineer or competent person before excavation. OSHA 29 CFR 1926 Subpart P governs all excavation work in the United States.