Grab Lorry Calculator

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.

UK road grab lorries come in two common classes. The 6-wheel grab is 26 tonnes gross vehicle weight (GVW) with roughly a 10m³ body and about 13 tonnes payload. The larger 8-wheel grab is 32 tonnes GVW with roughly a 13m³ body and about 16 tonnes payload — this is the typical lorry booked for muck-away. The actual load is often limited by weight rather than volume: dense materials like concrete rubble hit the payload limit well before the body is full.

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.

The 6-wheel grab lorry runs at 26 tonnes gross vehicle weight (GVW); after the unladen (tare) weight of roughly 13 tonnes, that leaves about a 13-tonne payload. The 8-wheel grab is 32 tonnes GVW and carries about 16 tonnes once its ~16-tonne tare is deducted. Smaller 18-tonne GVW grabs carry roughly 8 tonnes. Always check that the weight per load doesn't exceed the vehicle's payload capacity — overloading is an offence and the haulier will refuse it.

Grab lorry hire in the UK typically costs around £150-£420 per load (2026), depending on lorry size, location, material type and disposal requirements. As a rule of thumb a 6-wheel load runs about £290-£300 and an 8-wheel load about £340, excluding VAT. Clean inert soil/subsoil is cheapest to dispose of, while mixed and contaminated waste cost more. Prices vary by region — London and the South East are typically 20-30% more expensive than the North.