Overview
MOT Type 1 is commonly associated with the former MCHW Series 800 (Clause 803) terminology. The Manual of Contract Documents for Highway Works was restructured in September 2025, so check the current Specification for Highway Works and confirm your project's required depth and material with your contractor.
How the calculation works
Type 1 weight = area (m²) × compacted depth (m) × 2.2 t/m³ planning density, then any ordering and compaction allowances.
At 100mm compacted depth this works out to 0.22 tonnes (220kg) of Type 1 per square metre before allowances; at 150mm it is 0.33 tonnes.
Bag counts divide total kilograms by the bag's printed net weight and round up — most bulk bags are 850kg rather than a full tonne.
Worked example
A driveway 10m × 4m requires 150mm of compacted MOT Type 1.
Area = 40 m². Volume = 40 × 0.15 = 6.0 m³. Weight = 6.0 × 2.2 = 13.2 tonnes.
With a 10% allowance, order about 14.5 tonnes — a full 16-tonne grab load covers it with margin, or 18 × 850kg bulk bags.
MOT Type 1 at a glance
- Planning density2.20 t/m³
- Typical range2.00–2.30 t/m³
- CategorySub Base
- CompactionOften relevant
- SourcePlanning midpoint of published UK supplier data (≈2.0–2.3 t/m³ range observed)
- Reviewed2026-08-16
Planning values for typical UK supplies; your supplier product data takes precedence.
MOT Type 1 coverage guide
| Depth | Area per tonne | Area per 850kg bag | Weight per m² |
|---|---|---|---|
| 25mm | 18.2 m² | 15.5 m² | 55 kg |
| 40mm | 11.4 m² | 9.7 m² | 88 kg |
| 50mm | 9.1 m² | 7.7 m² | 110 kg |
| 75mm | 6.1 m² | 5.2 m² | 165 kg |
| 100mm | 4.5 m² | 3.9 m² | 220 kg |
| 150mm | 3.0 m² | 2.6 m² | 330 kg |
Computed from a 2.20 t/m³ planning density on level ground.
Assumptions and accuracy
2.2 t/m³ is a planning density for typical limestone Type 1; granite Type 1 and recycled Type 1 sit differently.
A retail bag labelled Type 1 does not automatically meet every project specification — check the certification your project requires.
Structural thicknesses are engineering decisions, not universal rules; confirm the specified layer and quantities with your contractor or supplier.
Planning density values
Use supplier product data whenever available. These figures are planning defaults shared by every calculator on the site.
| Material | Category | Planning density | Typical range | Compaction |
|---|---|---|---|---|
| MOT Type 1 | Sub Base | 2.20 t/m³ | 2.00–2.30 t/m³ | Relevant |
| MOT Type 3 | Sub Base | 2.10 t/m³ | 1.90–2.20 t/m³ | Relevant |
| Recycled Type 1 | Recycled | 2.00 t/m³ | 1.80–2.20 t/m³ | Relevant |
| 6F2 / 6F5 crushed aggregate | Recycled | 2.00 t/m³ | 1.80–2.20 t/m³ | Relevant |
| Road planings | Recycled | 2.00 t/m³ | 1.80–2.20 t/m³ | Relevant |
| Sharp sand | Sand | 1.60 t/m³ | 1.50–1.70 t/m³ | Usually no |
| Building sand | Sand | 1.50 t/m³ | 1.40–1.60 t/m³ | Usually no |
| Kiln-dried sand | Sand | 1.50 t/m³ | 1.40–1.60 t/m³ | Usually no |
| 10mm pea shingle | Gravel | 1.60 t/m³ | 1.40–1.70 t/m³ | Usually no |
| 20mm gravel / shingle | Gravel | 1.60 t/m³ | 1.40–1.70 t/m³ | Usually no |
| Decorative gravel | Decorative | 1.50 t/m³ | 1.30–1.70 t/m³ | Usually no |
| Slate chippings | Decorative | 1.60 t/m³ | 1.40–1.80 t/m³ | Usually no |
| Gabion stone | Gravel | 1.50 t/m³ | 1.40–1.60 t/m³ | Usually no |
| Self-binding gravel | Gravel | 1.90 t/m³ | 1.80–2.10 t/m³ | Relevant |
| Crushed concrete | Recycled | 1.90 t/m³ | 1.70–2.10 t/m³ | Relevant |
| Limestone scalpings | Sub Base | 2.00 t/m³ | 1.80–2.20 t/m³ | Relevant |
| Ballast | Sand | 1.70 t/m³ | 1.60–1.80 t/m³ | Usually no |
| Generic aggregate | General | 1.70 t/m³ | 1.50–2.20 t/m³ | Usually no |
How to use this calculator
- Enter the area to be sub-based and the specified compacted depth (commonly 100-150mm for vehicles).
- MOT Type 1 is preselected; switch to Type 3, recycled Type 1 or scalpings if specified.
- Enable the compaction allowance in Advanced options when ordering loose material.
- Compare bulk bag against loose-load cost using the price fields.
When MOT Type 1 is commonly used
MOT Type 1 is the default graded sub-base under block paving, asphalt, concrete slabs and gravel surfaces. MOT Type 3 is its free-draining cousin for permeable constructions; recycled Type 1 offers a lower-carbon alternative where the specification allows.
Frequently asked questions
How much MOT Type 1 per square metre?
At a 100mm compacted depth allow about 0.22 tonnes (220kg) per m²; at 150mm about 0.33 tonnes. Add your ordering allowance on top.
What depth of Type 1 do I need for a driveway?
Private driveways commonly use 100-150mm compacted, but the required depth depends on subgrade strength and expected loads. Check the specification for your project and confirm with your contractor.
How many bulk bags of Type 1 for 10 tonnes?
Twelve 850kg bulk bags hold 10.2 tonnes. At 800kg per bag you would need thirteen.
Is MOT Type 1 the same as Type 1 sub-base?
The terms are used interchangeably for the graded granular sub-base referenced in UK highway specifications. 'MOT' comes from the former Ministry of Transport; the current reference is the Specification for Highway Works published by Standards for Highways (the MCHW was restructured in September 2025 — Type 1 was formerly specified under Series 800).
What is MOT Type 3?
A coarser, free-draining sub-base with lower fines content than Type 1, used under permeable paving. It plans slightly lighter — around 2.1 t/m³ — and compacts less densely.
References and source notes
- Standards for Highways — current Specification for Highway Works (MCHW, restructured September 2025; granular sub-base formerly under Series 800), clauses for granular sub-base materials — standardsforhighways.co.uk
- Planning density from typical UK limestone Type 1 supplier data.