Skip to main content
Skip to main content

🚜 Excavation Calculator

Calculate excavation volumes for trenches, foundations, basements, and grading work.

Quick Formula​

Rectangular Excavation​

Volume (CY) = (Length × Width × Depth) ÷ 27

Trench Excavation​

Volume (CY) = (Length × Width × Depth) ÷ 27

Sloped Excavation​

Volume (CY) = Average Depth × Area ÷ 27

Common Calculations​

Example 1: Foundation Trench​

Trench: 100 linear feet × 2' wide × 3' deep

Calculation:

  • Volume = (100 × 2 × 3) ÷ 27
  • Volume = 600 ÷ 27 = 22.2 cubic yards

Example 2: Basement Excavation​

Basement: 40' × 30' × 8' deep

Calculation:

  • Volume = (40 × 30 × 8) ÷ 27
  • Volume = 9,600 ÷ 27 = 355.6 cubic yards

Example 3: Sloped Grading​

Area: 100' × 50' = 5,000 sq ft Average depth: 1.5 feet

Calculation:

  • Volume = (5,000 × 1.5) ÷ 27
  • Volume = 7,500 ÷ 27 = 277.8 cubic yards

Swell Factor​

Excavated material takes up more space than in-place material:

Material TypeSwell Factor
Sand1.10-1.15
Clay1.25-1.35
Rock1.35-1.50
Mixed1.20-1.30

Adjusted Volume:

Haul Volume = Excavation Volume × Swell Factor

Shrinkage Factor​

When compacting fill, material shrinks:

Material TypeShrinkage Factor
Sand0.90-0.95
Clay0.85-0.90
Mixed0.90-0.95

Fill Needed:

Fill Volume = Required Volume ÷ Shrinkage Factor
Account for Slopes

Excavation with slopes requires calculating average depth. Measure depth at multiple points and average them.