How to calculate excavation volume and truck loads

1. Volume in place

Volume (m³) = length × width × depth. If you dig wider than the footing or wall to work in, add the working space on each side to the length and the width.

2. Swell: volume to haul

Loosened soil takes more room than it had in the ground. Multiply the in-place volume by (1 + swell). The increase depends on the soil, often 15 to 40 %: measure or ask for your own soil, because the figure moves the number of loads.

• Trucks carry the loose volume: use it to count the trips.
• Backfill that is compacted goes the other way: it takes less room than the loose soil.

Worked example: 10 m × 8 m, 1.2 m deep

10 × 8 × 1.2 = 96 m³ in place. With 25 % swell: 120 m³ to haul.

• With an 8 m³ truck: 120 ÷ 8 = 15 loads.
• At 1.6 t/m³ in place, about 153.6 tonnes.

What this does not cover

The estimate assumes straight sides. Slopes, shoring, steps, rock, groundwater, access and disposal rules change the quantities and the cost. It is a planning estimate, not a geotechnical study or a foundation design.

For the concrete of the footings that go in the pit, use the concrete calculator.