Loose material compacts down — over-order a little so you don't run short.
MOT Type 1 is a 0–40mm crushed sub-base that compacts to a dense, load-bearing layer under driveways, patios, sheds and paths. It compacts down hard, so order 25–30% more than the loose volume suggests. Enter your area and finished depth to get the tonnage, then compare delivered prices from yards near you.
How to use this calculator
- Measure the area to cover in square metres (length × width).
- Set the finished, compacted depth — 100mm is typical for a domestic driveway, 150mm+ for vehicles.
- Keep the compaction allowance around 25–30% for Type 1 sub-base.
- Read off the tonnes and bulk bags, then get delivered quotes for that quantity.
How we work this out
We take your area and finished depth, work out the volume in cubic metres, then convert to weight using a loose delivered density of 2 tonnes per cubic metre for MOT Type 1 sub-base — the figure used across the UK trade. The compaction and wastage allowance is added on top so you don’t run short. Bulk-bag counts assume a standard 850 kg dumpy bag.
Delivered densities and coverage vary with grade, moisture and how hard the material is compacted, so these figures are a working estimate to size your order — always confirm the exact quantity and price with your supplier before buying. Our team reviews the density figures and guidance periodically; this page was last reviewed on 12 July 2026.
Frequently asked
How much MOT Type 1 do I need per square metre?
At 100mm compacted depth, roughly 0.25–0.3 tonnes of MOT Type 1 per square metre once you allow for compaction.
How deep should a Type 1 sub-base be?
Around 100mm for foot traffic and patios, 150mm for a domestic driveway, and 200mm+ where heavier vehicles will run.
How many bulk bags of Type 1 in a tonne?
A dumpy (bulk) bag holds roughly 0.7–0.85 tonnes, so a tonne is a little over one bulk bag.