What is a swell factor for excavated material?

Swell factor is the increase in volume when material is excavated from the ground. Soil in the ground (bank volume) expands when dug out because air voids are introduced. Typical swell factors: soil 25%, rubble 30%, concrete 40%, green waste 50%. A 10m³ hole in soil produces about 12.5m³ of loose material.

How much can a grab lorry carry?

Standard grab lorries have body capacities of 6m³ (small), 8m³ (standard), or 12m³ (large). However, the actual load may be limited by weight rather than volume. A standard 26-tonne GVW grab lorry with 12-tonne tare weight has a payload of 14 tonnes. Dense materials like concrete rubble will hit the weight limit before the volume limit.

How do I calculate the volume of material to remove?

Measure the excavation in metres: Length × Width × Depth = Volume in cubic metres. For example, a 5m × 4m × 0.5m excavation = 10 m³ of bank volume. Remember to apply the swell factor when calculating lorry loads — this 10m³ becomes about 12.5m³ of loose soil in the lorry.

What is the weight limit for a grab lorry?

Most grab lorries in the UK operate at 26 tonnes gross vehicle weight (GVW) on standard roads. With a typical tare weight of 12 tonnes, this gives a maximum payload of 14 tonnes. Smaller 18-tonne GVW grab lorries carry about 8 tonnes. Always check that the weight per load doesn't exceed the vehicle's payload capacity.

How much does a grab lorry cost to hire?

Grab lorry hire in the UK typically costs £250-£450 per load depending on location, material type, and disposal requirements. Clean soil/subsoil is cheapest to dispose of, while mixed waste and contaminated soil cost more. Prices vary by region — London and the South East are typically 20-30% more expensive than the North.

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Grab Lorry Calculator

Calculate grab lorry loads from volume, accounting for material swell factor and weight limits. Checks payload against GVW.

Bank Volume (in ground)

Volume measured in the ground before excavation

Material Type

Affects swell factor and density

Lorry Capacity

Body volume of the grab lorry

Price Per Load (optional)

Your haulier's price per load

How We Calculate This

This calculator determines the number of grab lorry loads by dividing the swelled volume by the lorry capacity, then cross-checks against the vehicle's weight payload limit to find the controlling factor.

The formula

Swelled volume = Bank volume × Swell factor
Loads (volume) = Swelled volume ÷ Lorry capacity
Loads (weight) = Total weight ÷ Max payload
Loads required = Greater of volume or weight loads

For 20m³ of soil: swelled = 20 × 1.25 = 25m³, weight = 20 × 1,600 = 32 tonnes. In an 8m³ lorry (14t payload): 4 loads by volume, 3 by weight — so 4 loads needed.

Material swell factors

Soil: 25% | Sand: 15% | Clay: 30%
Rubble: 30% | Concrete: 40%
Mixed waste: 35% | Green waste: 50%

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.