Overview
These are planning values, not universal physical constants — grading, moisture and compaction all move the real figure.
How the calculation works
Bulk density is mass per unit volume of aggregate including its voids: loose heaps have more air, compacted layers less. That single fact explains most conversion surprises.
To convert tonnes to m³ divide by density; to convert m³ to tonnes multiply. A 'medium' 1.7 t/m³ aggregate makes 2 m³ equal 3.4 tonnes.
Wet aggregate runs heavier per m³ than dry because water fills the voids without adding much volume.
Worked example
Converting 3 m³ of sharp sand (1.6 t/m³) to tonnes: 3 × 1.6 = 4.8 tonnes.
Converting 4 tonnes of slate chippings (1.6 t/m³) to volume: 4 ÷ 1.6 = 2.5 m³.
Compacting 1.2 m³ of Type 1 loose to a 100mm layer: about 2.2 × 1.2 = 2.64 tonnes before allowance adjustments.
Assumptions and accuracy
Table values are planning defaults compiled from typical UK supplier technical data.
Your supplier's product density takes precedence over any value here.
No generic density value is mandated by UK law; specifications reference material standards instead.
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
- Find your material in the density table; use the sorting to compare categories.
- Multiply volume by density for tonnage; divide tonnage by density for volume.
- Use the converter pages to run the arithmetic with your own figures.
When aggregate density is commonly used
Density values underpin every calculation on this site: calculator pages, the converters and bulk bag counts all read from the same table.
Frequently asked questions
What is the density of MOT Type 1?
Around 2.2 t/m³ compacted as a planning value (roughly 2,200 kg/m³). Recycled Type 1 plans nearer 2.0 t/m³.
What is the density of gravel in kg m3?
Typical UK gravel and shingle plan at 1,600 kg/m³ (1.6 t/m³); decorative gravels around 1,500 kg/m³.
Does moisture change aggregate density?
Yes — wet sand and gravel can weigh 15-20% more per cubic metre than dry for the same grading, which is why planning values carry ranges.
Which common aggregate is densest?
Compacted limestone and granite sub-bases sit highest at roughly 2.0–2.3 t/m³. Sands and gravels cluster around 1.5–1.7 t/m³, with lightweight decorative products the lowest.
References and source notes
- Planning densities compiled from UK supplier technical data sheets; treat as planning assumptions.
- Standards for Highways — current Specification for Highway Works (MCHW, restructured September 2025; granular sub-base formerly under Series 800) — standardsforhighways.co.uk