Calculate how much landscaping stone, decorative rock, or aggregate you need for gardens, paths and driveways — in tonnes and cubic metres, with cost.
| Item | Value |
|---|
Crushed rock and gravel are essential materials in Australian construction and landscaping. They are sold by weight (tonne) or volume (m³) depending on the supplier.
| Application | Material | Depth |
|---|---|---|
| Decorative garden bed | River stone / pebbles | 40–50 mm |
| Feature path | Crushed stone | 50–75 mm |
| Driveway topping | Blue metal / bluestone | 75–100 mm |
| Dry creek bed | Mixed river stone | 100–150 mm |
| Retaining backfill | Crushed rock | Varies |
| Gravel Type | Bulk Density | Common Use |
|---|---|---|
| Pea gravel / river pebbles | ~1.5-1.6 t/m³ | Garden beds, decorative |
| Crushed rock (20mm) | ~1.8-1.9 t/m³ | Driveways, drainage |
| Blue metal (20mm) | ~1.9-2.0 t/m³ | Concrete aggregate, driveways |
| Decomposed granite | ~1.6-1.8 t/m³ | Paths, driveways |
| Road base (compacted) | ~2.0-2.2 t/m³ | Sub-base for driveways |
| Application | Recommended Depth |
|---|---|
| Decorative garden bed | 40-50 mm |
| Landscaping path | 50-75 mm |
| Residential driveway | 75-100 mm over compacted base |
| Drainage layer | 100-150 mm |
How much stone do I need?
Work out the volume in cubic metres (length × width × depth in metres), then multiply by the stone density — typically 1.4–1.7 tonnes per cubic metre for landscaping stone. The stone calculator above does this for you and adds a wastage allowance. Always round up when ordering bulk stone.
How much area does a tonne of stone cover?
It depends on depth. At 50 mm deep, one tonne of decorative stone (about 1.5 t/m³) covers roughly 13 m². At 75 mm it covers about 9 m², and at 100 mm about 7 m². Deeper coverage means less area per tonne — the calculator shows your exact figures.
What depth of decorative stone should I use?
For decorative garden beds, 40–50 mm is usually enough to cover the soil. For paths and areas you walk on, 50–75 mm gives better coverage and stability. Driveways need 75–100 mm over a compacted base. Laying weed matting underneath first stops stone sinking into the soil.