Gravel by project
How much slate chipping for an 8 m2 border?
A decorative border estimate using slate chippings, a lower density assumption, and 20 kg bags.
Estimated result
Pre-calculated from the example inputs below. Adjust them in the calculator for your own numbers.
- Volume
- 0.32 m3 (0.42 yd3)
- Weight
- 0.46 t (0.5 US tons)
- Bag count
- 23 x 20 kg bags
An 8 m2 decorative slate border at 4 cm finished depth needs the volume, tonnes, and bag count shown below. Slate chippings can have a different density from pea gravel, so this example uses a lower density assumption and should be replaced with supplier data where available.
How to use this project example
This example uses a 8 m2 finished area at 4 cm depth. It estimates 0.32 m3 before applying density and allowance, so it is best used as a quantity check after the finished area and depth are decided.
- Measure inside the edging line or finished border, not the rough excavation area.
- Change the depth if the project needs more than decorative coverage.
- Split irregular shapes into sections and add the results together.
Ordering checks
The example uses 1.3 t/m3 density and 20 kg bags, giving 0.46 tonnes after allowance. Supplier bag weights, moisture, and delivery options can change the practical order.
- Compare small bags with bulk bags if the bag count becomes high.
- Check delivery access and where the aggregate can be dropped.
- Keep a small allowance for edging losses, settlement, and topping up.
8 m2 slate border gravel checks
| Input | Example value | Planning note |
|---|---|---|
| Area | 8 m2 | Finished surface area before depth is applied. |
| Depth | 4 cm | Changing depth changes volume directly. |
| Density | 1.3 t/m3 | Supplier figures should replace the default where available. |
| Order unit | 20 kg bags | 23 bags in this example after allowance. |
Example inputs used
- Length: 8
- Width: 1
- Depth: 4
- Aggregate density: 1.3
- Bag size: 20
These are starting values for this example. Measure or confirm your own figures, then open them in the gravel calculator.
Assumptions and limits
- Uses 8 x 1 m as a simple 8 m2 border.
- Uses 1.3 t/m3 as a planning density for slate chippings.
- Includes a 10% waste and settling allowance.
- Stone size and appearance may require a different finished depth.
This is an estimate. Site conditions, compaction, and aggregate type can change the final quantity.