MOT Type 1 sub-base calculator
Work out how much MOT Type 1 sub-base (also called hardcore) you need under a driveway, patio or shed base. Enter the area and depth and this calculator gives you the weight in tonnes, the bulk bags and the coverage.
MOT Type 1 sub-base calculator
Enter your measurements in metres. Everything updates as you type, and nothing is sent anywhere.
Based on a compacted MOT Type 1 density of about 2.1 tonnes per cubic metre and bulk bags of around 800kg, with 10% added for compaction and uneven ground. Allow about 100mm of sub-base under a patio and 150mm under a driveway, laid and compacted in 50mm layers.
Common questions
How much MOT Type 1 do I need?
Multiply the area by the depth for the volume, then by about 2.1 for the weight in tonnes. At 100mm deep, one tonne of MOT Type 1 covers roughly 5 square metres once compacted. The calculator adds 10% for compaction and uneven ground.
Is hardcore the same as MOT Type 1?
MOT Type 1 is a graded crushed stone sub-base, and it is what most people mean by hardcore for a modern driveway or patio. It compacts to a solid, level base. Old broken brick and rubble is also called hardcore but does not compact as cleanly, so Type 1 is the standard choice.
How deep should the sub-base be?
About 100mm compacted under a patio or shed base, and 150mm under a driveway that takes a car. Lay and whacker-plate it in layers of no more than 50mm at a time so it compacts properly.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing. These quantities are a guide to help you order. Always round up and check with your supplier before buying.