Excavation Calculator
Estimates excavation volume in cubic metres and soil tonnes for a dig.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the length, width and depth.
- Press Calculate.
How it works
Volume = length × width × depth; spoil weight ≈ volume × 1.8 tonnes per m³.
Worked example
4 × 5 × 0.5 m. = 10 m³ ≈ 18 tonnes.
Common mistakes
- Forgetting that dug soil bulks up — spoil takes about 20–30% more volume than the hole.
- Ignoring batter (sloped sides) needed for deep or unstable trenches.
Frequently asked questions
How is excavation volume calculated?
Length × width × depth gives the in-ground volume; the tool can also estimate the bulked spoil to cart away or stockpile.
Why is there more spoil than the hole?
Excavated soil loosens and bulks up — typically 20–30% — so always plan disposal for more volume than you dug.
Why is the spoil more than the hole I dug?
Excavated material 'bulks up' (swells) by roughly 20–30%, so you cart away more loose volume than the in-ground volume.
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Cite this tool
Zerdly. (2026). Excavation Calculator. Retrieved from https://www.zerdly.com/tools/excavation-calculator/
Tip: Enter any known values to calculate the remaining results.
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