MOT Type 1 sub-base calculator

MOT Type 1 is the crushed-stone sub-base that goes under driveways, patios, paths, and sheds to create a strong, well-draining foundation. This calculator works out how much you need: enter the length, width, and compacted depth, and it returns the area, volume, weight in tonnes, and the number of bulk bags to order.

How much MOT Type 1 do I need?

The calculation is area × depth, using a compacted density of about 2.1 tonnes per cubic metre for MOT Type 1. Recommended depths are typically 100 mm (10 cm) for pedestrian paths and patios, and 150 mm (15 cm) or more for driveways that take vehicles. Because the material compacts, it is wise to order a little extra.

Laying the sub-base

Spread MOT Type 1 in layers of around 75–100 mm and compact each layer with a plate compactor (wacker plate) before adding the next. A properly compacted sub-base prevents sinking and rutting later. Once it is down, calculate your surface layer with our gravel calculator, concrete calculator, or paving calculator. See also our full Type 1 MOT guide.

Frequently asked questions

How deep should MOT Type 1 be for a driveway?

Usually 150 mm (15 cm) of compacted Type 1 for a domestic driveway, increasing to 200 mm for heavier vehicles or soft ground.

Disclaimer: Estimates only. Ground conditions vary — confirm depths and quantities with your supplier or contractor.