Spoil Pile Calculator

This spoil pile calculator estimates the physical dimensions of an excavated material pile to help plan staging areas and ensure OSHA compliance. If you still need the source bank volume, use the excavation calculator first.

For workflow examples that show how excavation output turns into real staging decisions, see spoil pile examples. This page models the pile as a cone based on the loose volume and the angle of repose.

Cone Model

Loose excavated material naturally forms a conical shape. The cone geometry formulas below match the workflow explained in the excavation formulas guide:

• Volume: V = (1/3) × π × r² × h
• Height: h = r × tan(angle of repose)
• Radius: r = ³√(3V / (π × tan(angle)))

Swell Factor

The loose volume is larger than the bank (in-ground) volume because soil expands when excavated. The loose volume = bank volume × (1 + swell%/100). This expanded volume determines the pile size. If you want the underlying bank-to-loose conversion steps, review the excavation formulas guide.

OSHA Setback Requirement

Per OSHA 29 CFR 1926.651(j)(2), excavated material must be placed at least 2 ft (0.6 m) from the edge of the excavation. The total staging area includes this setback ring around the pile: Total Area = π × (radius + 0.6 m)².