Overview
Buyers order in tonnes but sites measure in metres — this converter bridges the two without long division.
How the calculation works
Volume (m³) = weight (tonnes) ÷ density (t/m³). The division simply asks how many cubic-metre blocks of that material make up the tonnage.
Density is the pivot: 1.6 t/m³ gravel converts a tonne to 0.625 m³, while 2.2 t/m³ Type 1 converts the same tonne to 0.455 m³.
Results are planning volumes — loose loads fluff up and compacted layers pack down against these figures.
Worked example
A delivery note shows 4 tonnes of 20mm gravel.
Volume = 4 ÷ 1.6 = 2.5 m³. Laid 50mm deep this covers 2.5 ÷ 0.05 = 50 m².
The same 4 tonnes as MOT Type 1 would be 4 ÷ 2.2 = 1.82 m³ — 27% less volume.
20mm gravel / shingle at a glance
- Planning density1.60 t/m³
- Typical range1.40–1.70 t/m³
- CategoryGravel
- CompactionUsually not applied
- SourcePlanning value based on typical UK 20mm shingle bulk densities
- Reviewed2026-08-16
Planning values for typical UK supplies; your supplier product data takes precedence.
20mm gravel / shingle coverage guide
| Depth | Area per tonne | Area per 850kg bag | Weight per m² |
|---|---|---|---|
| 25mm | 25.0 m² | 21.3 m² | 40 kg |
| 40mm | 15.6 m² | 13.3 m² | 64 kg |
| 50mm | 12.5 m² | 10.6 m² | 80 kg |
| 75mm | 8.3 m² | 7.1 m² | 120 kg |
| 100mm | 6.3 m² | 5.3 m² | 160 kg |
| 150mm | 4.2 m² | 3.5 m² | 240 kg |
Computed from a 1.60 t/m³ planning density on level ground.
Assumptions and accuracy
Planning densities are used; supplier product data takes precedence.
Loose and compacted volumes differ — the converter returns the uncompacted planning volume.
For the reverse direction use the cubic metres to tonnes converter.
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 weight in tonnes (decimals allowed).
- Pick the material so the right planning density applies.
- Read the volume in cubic metres.
- Divide the volume by your layer depth in metres to get coverage in m².
When aggregate is commonly used
Converting delivery tickets into coverage, checking whether a quoted load fills the intended depth, and translating grab-lorry capacities (usually quoted in m³) into orderable tonnes.
Frequently asked questions
How many cubic metres is 1 tonne of gravel?
About 0.63 m³ for standard 20mm gravel at 1.6 t/m³. A 10-tonne load is roughly 6.3 m³.
How many m3 in a tonne of Type 1?
About 0.45 m³ compacted planning volume at 2.2 t/m³ — denser than gravel, so the same tonnage occupies less space.
Why does my load look smaller than the conversion?
Compaction. Loose delivered volume settles when compacted; planning conversions sit between the two. Judge the finished depth, not the heap.
How many cubic metres is 10 tonnes of Type 1?
Divide weight by density: 10 ÷ 2.2 ≈ 4.55 m³ of compacted planning volume. The converter above applies the same arithmetic to any material and tonnage.
References and source notes
- Conversion densities from the aggregate planning density table on this page.