What is the swell factor for excavation?

Swell factor is the increase in volume when soil is excavated and loosened. Topsoil swells by 10% (factor 1.1), clay by 30% (1.3), sand/gravel by 15% (1.15), chalk by 20% (1.2), and rock by 40% (1.4). You need to account for swell when calculating lorry loads and disposal volumes, as the excavated material takes up more space than in the ground.

How many lorry loads for my excavation?

Divide the swelled volume by the lorry capacity. A standard 8-wheeler tipper carries approximately 8 m³ (16 tonnes). A 6-wheeler carries 6 m³ (10 tonnes). For a typical 50 m³ clay excavation: 50 × 1.3 swell = 65 m³ swelled, needing 9 loads in an 8-wheeler. Always round up to whole loads.

How long does excavation take?

A mini digger (1.5-3 tonne) excavates approximately 5-8 m³ per hour in normal conditions. A larger 8-tonne excavator can manage 15-25 m³ per hour. Productivity varies with soil type (rock is slower), depth, access, and weather. Allow extra time for setting up, moving equipment, and loading lorries.

How much does excavation disposal cost?

Disposal costs in the UK vary by soil type and location. Clean topsoil/subsoil: £150-250 per lorry load. Contaminated soil: £350-600+ per load requiring specialist disposal. Landfill tax adds significantly to costs. If the soil is clean, consider offering it free for collection or reusing it on site to reduce disposal costs.

What is the density of excavated soil?

Soil density varies by type: topsoil approximately 1.6 t/m³, clay 1.8-2.0 t/m³, sand/gravel 1.8 t/m³, chalk 1.7 t/m³, rock 2.0-2.5 t/m³. These are in-ground densities — the weight per cubic metre matters for lorry payloads. An 8-wheeler can carry 16 tonnes, so with clay at 1.9 t/m³, it can carry about 8.4 m³ by weight.

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Groundwork Excavation Calculator — Volume, Swell & Lorry Loads

Calculate cut volume, swell factor by soil type, lorry loads and disposal costs for groundwork excavation.

Excavation Length

Excavation Width

Average Depth

Average depth of excavation

Soil Type

Swell factor: ×1.3

Lorry Type

Disposal Price per Load

Digger Hire Price

How We Calculate This

This calculator determines the cut volume, swelled volume, lorry loads and costs for groundwork excavation.

Volume and swell

Cut Volume = Length x Width x Depth
Swelled Volume = Cut Volume x Swell Factor
Swell factors: topsoil 1.1, clay 1.3, sand/gravel 1.15, chalk 1.2, rock 1.4.

Lorry loads

Loads = ceil(Swelled Volume / Lorry Capacity)
8-wheeler: 8 m³, 6-wheeler: 6 m³, artic: 12 m³.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.