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 quantities are a guide to help you order. Always round up and check with your supplier before buying.