Gravel and aggregate density guide
Last reviewed 1 July 2026
Short answer
Most construction aggregates sit between 1,300 and 2,100 kg/m³ loose. Gravel and crushed stone are around 1,600, sub-base around 2,000, and slate as low as 1,300 because the flat particles do not pack tightly. Every figure is a range, not a constant — moisture alone moves it by up to 10%.
Work it out for your project with the gravel calculator →
Bulk density table
| Material | Typical | Range | Notes |
|---|---|---|---|
| 20 mm gravel / ¾ in gravel | 1,600 kg/m³ | 1,500–1,700 | The default for paths and decorative areas |
| Pea gravel / pea shingle | 1,600 kg/m³ | 1,500–1,700 | Rounded; migrates underfoot |
| Crushed stone / angular chippings | 1,600 kg/m³ | 1,500–1,750 | Interlocks, so it holds a driveway |
| Limestone chippings | 1,550 kg/m³ | 1,500–1,650 | Dusts down and beds in over time |
| MOT Type 1 sub-base | 2,000 kg/m³ | 1,900–2,100 | Quoted loose; gains density when compacted |
| Road base / dense graded base (US) | 2,100 kg/m³ | 1,950–2,200 | The US equivalent of Type 1 |
| Slate chippings | 1,300 kg/m³ | 1,250–1,400 | Plate-shaped, so it packs poorly and covers more |
| Decorative stone | 1,500 kg/m³ | 1,400–1,650 | Varies widely; check the bag |
| Sharp sand / concrete sand | 1,600 kg/m³ | 1,500–1,700 | Bulks up when damp |
| Building sand / mason sand | 1,500 kg/m³ | 1,400–1,600 | Soft sand for mortar |
| Screened topsoil | 1,300 kg/m³ | 1,100–1,500 | Very wet soil can exceed the range |
These are loose bulk densities as delivered — the figure you want when converting a volume into a weight to order.
Three densities, easily confused
Quoting particle density instead of bulk density is a common error and produces answers about 60% too heavy.
- Particle density is the density of the rock itself, typically 2,600–2,700 kg/m³. It is not useful for ordering.
- Loose bulk density includes the air between the particles. This is what a supplier's tipper delivers and what these tables give.
- Compacted bulk density is what you get after a plate compactor. It is higher than loose, which is exactly why the compaction allowance exists.
Why slate behaves differently
Slate chippings are flat plates rather than lumps. Stacked loosely they trap far more air, which is why the bulk density is around 1,300 kg/m³ against 1,600 for gravel.
The practical effect is that a tonne of slate covers noticeably more ground than a tonne of gravel — about 23% more at the same depth. If you switch material after pricing the job by weight, recheck the coverage.
Using ranges properly
If you are ordering by volume, use the middle of the range and check the weight is within your delivery limits.
If you are ordering by weight and cannot afford to be short — because you are covering a fixed area to a fixed depth — use the top of the range. A denser load means fewer cubic metres for the same tonnage.
If you are checking whether a vehicle can carry it, use the top of the range plus the moisture allowance.
Note: Ask the supplier
Safety notice: Material planning only