Calculate how much landscaping stone, decorative rock, or aggregate you need for gardens, paths and driveways — in tonnes/m³ (metric) or tons/cubic yards (US), with cost.
Enter your area and stone depth below and pick your units — the calculator works out the volume and weight of stone you need, plus an estimated cost, whether you buy by the tonne (AU) or the cubic yard (US).
| 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 |
Say you’re covering a garden bed 6 metres long and 2.5 metres wide with river pebbles at 50 mm deep. The area is 6 × 2.5 = 15 m². Multiply by the depth: 15 × 0.05 = 0.75 m³. River pebbles have a density around 1500 kg/m³, so that’s 0.75 × 1500 = 1125 kg, or about 1.13 tonnes. Adding 10% for wastage brings it to roughly 1.24 tonnes — so you’d order 1.25 tonnes of pebbles.
The stone you pick changes both the look and the quantity you’ll need, because different stones have different densities and are laid at different depths. Decorative river pebbles and white pebbles are popular for garden beds and around feature plants, laid fairly shallow at 40–50 mm. Crushed rock and blue metal are more angular, lock together well, and suit paths and driveways where you want a firm surface — these go deeper at 75–100 mm. Scoria, a lightweight volcanic rock, is often used where weight matters, such as on rooftop gardens or over drainage. Sandstone and granite toppings sit in between, chosen mainly for their colour.
A common mistake is ordering by area alone and forgetting depth. Two beds of the same size need very different amounts of stone if one is a shallow decorative layer and the other a deep driveway topping. Another is underestimating wastage — stone settles, spreads unevenly, and some is always lost during spreading, so the 10% margin this calculator adds is worth keeping. Finally, if you’re topping up existing stone rather than starting fresh, measure only the depth you’re adding, not the full target depth, or you’ll over-order.
| 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 (1.5-2 in) |
| Landscaping path | 50-75 mm (2-3 in) |
| Residential driveway | 75-100 mm (3-4 in) over compacted base |
| Drainage layer | 100-150 mm (4-6 in) |
Landscaping stone is measured and sold differently depending on the market. In Australia and the UK, suppliers price by the tonne and quote volume in cubic metres (m³). In the United States, stone yards price by the cubic yard and weigh out in US (short) tons. Use the Metric/US toggle above the calculator to switch — it converts every field and result automatically.
| Measure | Australia / Metric | United States |
|---|---|---|
| Volume unit | Cubic metre (m³) | Cubic yard (cu yd) |
| Weight unit | Tonne (1,000 kg) | US ton / short ton (2,000 lb) |
| Conversion | 1 m³ = 1.308 cu yd | 1 cu yd = 0.765 m³ |
| Conversion | 1 tonne = 1.102 US tons | 1 US ton = 0.907 tonnes |
| Typical yield | ~1.5-1.7 tonnes per m³ | ~1.2-1.4 US tons per cu yd |
How much stone do I need?
Work out the volume (length × width × depth), then multiply by the stone's bulk density — typically 1.4–1.7 tonnes per cubic metre (about 1.2–1.4 US tons per cubic yard) for landscaping stone. The calculator above does this automatically and adds a wastage allowance in either metric or US units.
How much area does a tonne (or ton) of stone cover?
It depends on depth. At 50 mm (2 in) deep, one tonne of decorative stone covers roughly 13 m² (about 140 sq ft); a US ton covers a similar order of magnitude, around 110-130 sq ft at the same depth. At 75-100 mm (3-4 in) coverage drops to roughly 7-9 m² per tonne. The calculator shows your exact figures for the depth you enter.
What depth of decorative stone should I use?
For decorative garden beds, 40-50 mm (1.5-2 in) is usually enough to cover the soil and suppress weeds. Paths and areas you walk on need 50-75 mm (2-3 in) for stability, and driveways need 75-100 mm (3-4 in) over a compacted base. Laying weed matting underneath first stops stone sinking into the soil.
Is stone sold by weight or by volume?
In Australia, landscaping stone is almost always sold by the tonne. In the US, most stone yards sell by the cubic yard instead. This calculator gives you both the volume and the weight in whichever unit system you choose, so you can order correctly either way.
Can I use this calculator for pebbles and crushed rock?
Yes. Select the stone type — decorative pebbles, crushed rock, blue metal, sandstone, granite or scoria — and the calculator applies that material's density so the weight is accurate for what you're actually buying.
How many cubic yards of stone do I need?
Switch the calculator to US units, enter your area in feet and your depth in inches, and it converts directly to cubic yards for you. As a rule of thumb, one cubic yard covers about 100 sq ft at 3 in deep, or about 160 sq ft at 2 in deep.
How much does a cubic yard of stone weigh?
Most crushed stone and gravel weighs around 2,400-2,700 lbs (1.2-1.35 US tons) per cubic yard, though denser materials like blue metal or road base can weigh more. The calculator's US mode converts your volume to US tons using the density you select.