Excavation Volume Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/9/2026
The volume to excavate is calculated with length × width × depth. A 5 × 3 × 1.2 m pit represents a volume of 18 m³ of soil to remove.
Explanation
This calculator gives the gross volume of soil to excavate for a pit (foundation footing, pool, basement) or a trench (pipe run, drainage), from its three dimensions. This volume serves as the basis for several upfront estimates before a job: the excavation time needed, the volume of soil to haul away or reuse on site (as backfill, for example), the right size of excavation equipment, and — once the pit is ready — the amount needed from our concrete mix calculator for the foundation poured into it. One point to keep in mind: excavated soil generally occupies a larger volume once out of the ground than its in-place volume, a phenomenon called bulking (the soil loses its natural compactness) — the bulking factor varies by soil type (often 15 to 30% extra volume for common soil, more for clay or fragmented rock), to be accounted for separately when sizing the number of skips or trucks needed for hauling. This calculator gives the in-place volume, before bulking.
Example: a 5 × 3 × 1.2 m pit
Inputs
Length: 5 m. Width: 3 m. Depth: 1.2 m.
Calculation
Volume = 5 × 3 × 1.2 = 18 m³.
Result
This pit requires excavating 18 m³ of soil.
Frequently asked questions
What is soil bulking and why does it matter?
Bulking is the increase in volume soil undergoes once excavated, since it loses the compactness it naturally had in place in the ground. Common soil typically bulks by 15 to 30%, meaning 18 m³ of in-place soil can become 21 to 23 m³ once excavated — a key factor for correctly sizing the number of skips or trucks needed for hauling.
Does this volume directly match the amount of concrete needed for the foundation?
No, this calculator gives the total volume of the pit, not the volume of concrete that will be poured into it: a foundation generally occupies only part of the pit (the rest can be filled with gravel, backfill, or left as a crawl space). For the concrete volume specifically, see our concrete volume calculator.
How do you estimate the excavation depth needed for a foundation?
Foundation depth depends on the soil type, local climate (frost depth), and construction type, and is determined by a soil survey or local building code recommendations. This calculator doesn't determine that depth: it only calculates the volume once the three dimensions are known.