How much MOT Type 1 do I need?
Area × compacted depth × 2.1 tonnes per m³, plus about 10%. A 20m² patio at 100mm is 2m³, which is 4.2 tonnes, or 4.6 with waste: 6 bulk bags of 800kg or a 5-tonne loose load.
How much does a tonne of MOT Type 1 cover?
| Compacted depth | 1 tonne covers | An 800kg bag covers | Typical use |
|---|---|---|---|
| 75mm | 6.3m² | 5.1m² | Path |
| 100mm | 4.8m² | 3.8m² | Patio or path |
| 150mm | 3.2m² | 2.5m² | Driveway |
| 200mm | 2.4m² | 1.9m² | Heavy vehicles or soft ground |
Loose or compacted: why the figures differ
Type 1 is a mix of crushed stone and fines that packs down when it is compacted with a plate or roller, so a tonne fills less space once it is down. Calculators disagree because some work from the loose figure and some from the compacted one. This one orders by the compacted depth at 2.1 tonnes per m³. Pavingexpert gives about 5m² per tonne at 100mm and 3.5m² at 150mm, so 2.1 errs slightly on the side of too much, which is better than running short with the plate hired for the day.
How deep should MOT Type 1 be?
- 75 to 100mm under a path or patio on firm ground (Mainland Aggregates).
- 150mm under a domestic drive (Howmuchgravel; materialcalculator).
- 200mm or more for heavy vehicles or soft ground (materialcalculator).
Lay and compact it in layers rather than all at once, so the bottom is as firm as the top. IBRAN's gravel grid guide compacts 150mm in 50mm layers.
Type 1 or Type 3?
Type 1 has fines that fill the gaps, so it compacts hard but does not drain well. Type 3 has fewer fines, so water passes through it: it is used under permeable paving. It weighs a little less per m³, so ask your supplier for their figure and put it into the density box.
How much does MOT Type 1 cost?
Howmuchgravel's 2026 guide puts it at £25 to £40 a tonne loose, plus delivery. Bulk bags cost more per tonne than a tipper load, but are easier to get onto a tight site.
Frequently asked questions
How much does 1 tonne of MOT Type 1 cover?
About 4.8m² at 100mm compacted and 3.2m² at 150mm.
Is MOT Type 1 the same as hardcore?
People use the names loosely. MOT Type 1 is a graded crushed stone made to a Highways specification, so it compacts evenly. Mixed hardcore varies from load to load.
Do I need a membrane under Type 1?
It helps on soft or clay ground, keeping the soil and the stone apart. Breedon and IBRAN both put the membrane on the ground, under the sub-base.
Does the calculator work in feet and inches?
Yes. Switch any length to ft/in. Depths are in millimetres: 4 inches is about 100mm and 6 inches about 150mm.
Sources
- materialcalculator.co.uk: gravel densities and depths (reviewed 7 Sep 2026) (opens in a new tab)
- Mainland Aggregates: how much gravel do I need (4 Jun 2026) (opens in a new tab)
- Howmuchgravel: gravel driveway cost 2026 (opens in a new tab)
- Pavingexpert: sub-base aggregates, Type 1 coverage (opens in a new tab)
- Breedon: Golden Amber self-binding gravel FAQs (opens in a new tab)
- IBRAN: how to lay gravel grids (opens in a new tab)
Quantities are estimates for ordering. Soft ground and heavy vehicles need a deeper base: ask your supplier or an engineer.
By Janusz Wozniak, Founder & Lead Developer
Built because Type 1 calculators disagree by a fifth, and nobody says why. This one shows the figure it uses and where it comes from.
Last updated .
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