Aggregate calculator
Work out how much aggregate you need in tonnes and 850kg bulk bags, in metres and millimetres, at UK laying depths.
Aggregate calculator
Use your supplier's density
You need
- Volume
- Weight
- Area
| Order by | Exact | Order, rounded up for anything sold in whole bags |
|---|
Enter your measurements to see what to order.
One cubic metre of aggregate weighs about 1.6 tonnes and covers about 22 square metres at 45mm.
How to work out how much aggregate you need
- Measure the area in metres and multiply length by width.
- Pick a depth in mm and multiply it by the area to get a volume.
- Multiply the volume by the bulk density, 1600 kg per cubic metre for aggregate, to get a weight.
- Divide the weight by your supplier's tonne or bulk bag to get what to order, and round up. Suppliers do not sell part bags.
- Add 10 percent. Covers settlement, uneven ground and the material lost around the edges. A second delivery for half a yard costs more than the extra you did not use.
How many tons in a cubic yard of aggregate?
About 1.35 US tons, at 1600 kg per cubic metre. Because published densities run from 1500 to 1700, the honest answer is a range: between 1.26 and 1.43 tons per cubic yard depending on grading and how wet the load is.
How many cubic yards in a ton of aggregate?
About 0.74 cubic yards. One tonne is about 0.63 cubic metres.
How deep should aggregate be laid?
| Use | Depth | What the supplier says |
|---|---|---|
| Path | 40mm to 50mm | Mainland Aggregates: 20mm gravel should be laid at no more than 40 to 50mm depth. |
| Driveway | 40mm to 50mm | Mainland Aggregates: spread over a compacted sub-base such as Type 1. |
| Border | 40mm to 50mm | Mainland Aggregates. |
How much does aggregate weigh?
Between 1500 and 1700 kg per cubic metre, a spread of 13 percent. UK 20mm decorative gravel. Merchants publish this as coverage, typically one bulk bag over 10 square metres at 50mm. The calculator above uses 1600, and you can replace it with your own supplier's figure.
4 published figures from 3 suppliers, read 2026-09-20.
| Supplier | Published figure | Condition |
|---|---|---|
| Mainland Aggregates LtdUK | Approx 1.7 tonnes per cubic metre | unstated |
| Stones4GardensUK | 1,600 kg/m3 | unstated |
| Stone WarehouseUK | 1.00 Bulk Bags (800kg) = 10m2 approx., stated for gravel and chippings at 50mm depth | unstated |
| Mainland Aggregates Ltd (coverage figure, same product page)UK | 1 x Bulk Bag will cover approx 10sqm at 50mm depth (bulk bag stated as 850kg) | unstated |
What you can order aggregate in
| Pack | Where | Size |
|---|---|---|
| 850kg bulk bag | UK | 850 kg (suppliers state 700 to 1000 kg) |
| 25kg bag | UK | 25 kg |
| tonne | UK, AU | 1,000 kg |
Aggregate and gravel
In the US trade the same material is sold as gravel, ordered in cubic yards and tons, so the gravel calculator works in those units and at those depths.