How much MOT Type 1 do I need?
The exact amount of aggregate you need will depend heavily on the length, width, and depth of the area you intend to cover. Converting this physical volume into a measurable weight (tonnes) requires understanding the density of MOT Type 1.
Our calculator handles this complicated conversion seamlessly. Using an industry-standard estimate for sub-base density, it takes your dimensions, calculates the volume, applies an appropriate wastage buffer, and reliably estimates the number of tonnes or bags you should order.
Typical MOT Type 1 depths
| Project Type | Typical Depth |
|---|---|
| Path | 75 mm |
| Patio | 100 mm |
| Driveway | 150 mm |
| Shed Base | 100 mm |
Note: Heavy vehicles or working on exceptionally weak ground may require a greater depth for adequate stability.
MOT Type 1 calculator formula
• Volume (m³) = Length × Width × Depth
• Volume with Wastage = Volume × (1 + Wastage %)
• Tonnes Required = Volume with Wastage × Density
What is MOT Type 1?
It is a compactable granular sub-base, officially approved by the Ministry of Transport (hence "MOT"). It is commonly made from crushed granite or limestone, containing pieces up to 40mm right down to dust. When heavily compacted, the dust binds the larger stones together, forming an excellent, frost-resistant, load-bearing layer beneath paving or surfacing.
Why tonnage estimates vary
Several real-world factors can lead to slight discrepancies in your ordered quantity vs the required amount.
- Moisture Content: Wet aggregate is heavier than dry.
- Compaction: Highly compacted sub-bases use more aggregate.
- Supplier Grading: Variances exist between quarries.
- Ground Conditions: Uneven foundations can require thicker layers.
- Waste: Spillage naturally occurs during spreading.
Frequently Asked Questions
What is MOT Type 1 used for?
MOT Type 1 is used as a compactable sub-base under driveways, patios, paths, roads, and other hard surfaces. It provides a stable, load-bearing layer.
How deep should MOT Type 1 be for a driveway?
A typical domestic driveway often uses around 150 mm of MOT Type 1, though heavier loads or weaker ground may require more depth to ensure structural stability.
How do I calculate MOT Type 1 tonnage?
Multiply the length by width by depth to get the volume in cubic metres, then multiply by the material density (usually around 2.0 to 2.1 t/m³) to estimate the tonnes required.
How many tonnes of MOT Type 1 are in a cubic metre?
A common estimate is around 2.0 to 2.1 tonnes per cubic metre. However, the exact density can vary depending on the supplier, grading, and moisture content.
Should I add extra for wastage?
Yes. Adding 5% to 10% wastage is a practical way to account for site specific ground variations, compaction settlement, and to broadly reduce the risk of under-ordering.
Compare material quantities before ordering
It is usually safer to round up slightly to avoid under-ordering and facing mid-project delays.