Excavation Cost Calculator
Estimate earthmoving volume in cubic yards and total excavation cost by entering pit dimensions, soil difficulty, and contractor pricing. Useful for foundations, pools, and utility trenches.
About this calculator
Excavation volume is measured in cubic yards. Because dimensions are entered in feet, the raw cubic-foot volume must be divided by 27 to convert to cubic yards. Harder soils — dense clay, compacted gravel, or rocky ground — require more machine time and wear, so a soil difficulty multiplier adjusts the cost accordingly. A soft sandy soil might have a multiplier of 1.0, clay around 1.25, and rocky ground 1.5 or higher. The formula is: Cost = (excavationLength × excavationWidth × excavationDepth / 27) × soilType × costPerCubicYard. Note that this gives material removal cost only; hauling, disposal tipping fees, and shoring are typically billed separately by contractors.
How to use
Say you need to excavate a 30 ft × 20 ft foundation pit to a depth of 4 ft in clay soil (difficulty factor 1.25) at a contractor rate of $40/yd³. Step 1 — volume in cubic feet: 30 × 20 × 4 = 2,400 ft³. Step 2 — convert to cubic yards: 2,400 / 27 ≈ 88.89 yd³. Step 3 — apply soil factor: 88.89 × 1.25 = 111.11 yd³ (effective). Step 4 — total cost: 111.11 × $40 = $4,444. Budget approximately $4,444 for this excavation, before hauling and disposal.
Frequently asked questions
How do contractors calculate excavation cost per cubic yard?
Contractors start with the excavated volume in cubic yards, then adjust for soil type, required depth, and site accessibility. Soft soils that a machine can scoop quickly are cheapest; dense clay, caliche, or rock that requires blasting or hydraulic hammers cost significantly more per yard. Most quotes also include a mobilization fee for transporting equipment to the site, which can range from a few hundred to several thousand dollars depending on distance. Always ask whether the quoted rate includes spoil removal and dump fees, as those are sometimes billed separately.
What is a soil type difficulty multiplier in excavation estimating?
The soil difficulty multiplier is a coefficient that scales the base excavation cost to reflect how hard the material is to remove. A value of 1.0 represents loose, sandy, or loamy soil that a standard excavator bucket moves quickly. Clay, which sticks to equipment and is denser, typically earns a multiplier of 1.2–1.4. Heavily compacted gravel or weathered rock might be 1.5–2.0, while solid bedrock requiring blasting can push the multiplier to 3.0 or more. Your excavation contractor can advise on the appropriate factor after a site assessment.
How do I convert excavation volume from cubic feet to cubic yards?
One cubic yard equals 3 ft × 3 ft × 3 ft = 27 cubic feet. To convert, simply divide your cubic-foot volume by 27. For example, a trench that is 50 ft long, 2 ft wide, and 3 ft deep contains 50 × 2 × 3 = 300 cubic feet, which equals 300 / 27 ≈ 11.1 cubic yards. This matters because excavation contractors, disposal sites, and dump trucks all price by the cubic yard. Entering accurate dimensions into this calculator will handle the conversion automatically.