Excavation Calculator
Estimate soil removal volume for trenches, basements and foundations, including swell/shrink.
How to use this tool
- Choose the excavation type (trench, pit, or slab area/deep).
- Enter length, width and depth (or area and depth).
- Set the swell percentage (default 25%).
- Optionally add disposal cost per unit.
- Calculate bank volume, loose volume and disposal cost.
How it works
Bank volume = length x width x depth. Loose volume = bank volume x (1 + swell/100). Cost is applied to the loose volume you actually haul.
Tips
- Swell of clay is higher (~30%) than sand (~15%).
- Backfilling uses compacted volume — plan extra for compaction loss.
- Include access and benching for safe working.
Limitations
Does not account for groundwater or rock — those change productivity and pricing significantly.
Frequently asked questions
What is swell factor?
When soil is dug loose, it occupies more volume than in place — typically 20–30% for common soil. Use swell to plan truck loads and disposal.
How is trench volume calculated?
Trench volume = length x average width x depth. For sloping sides, use the average width at mid-height.
Do I compute loose vs bank volume?
The calculator shows both: bank (in-place) volume you dig, and loose volume you haul away after swell.