Ordering bulk landscape supplies is far cheaper than buying bags, but it only pays off if you get the quantity right. Order too little and you're back at the yard mid-job; order too much and you're left with a pile on the driveway. Here's how to work it out in a couple of minutes.
The basic formula
All Daltons bulk products are sold by volume, in half cubic metre (½ m³) lots. To work out the volume you need:
Length (m) × Width (m) × Depth (m) = Volume (m³)
The trick is to convert the depth to metres: 100mm is 0.1m, 75mm is 0.075m and 50mm is 0.05m.
Example: a garden bed 4m long and 1.5m wide, mulched with bark 75mm deep, needs 4 × 1.5 × 0.075 = 0.45 m³. One ½ m³ lot will do the job.
If you'd rather not do the maths, our volume calculator does it for you.
How far does ½ m³ go?
| Depth |
Area covered by ½ m³ |
Area covered by 1 m³ |
| 25mm |
20 m² |
40 m² |
| 50mm |
10 m² |
20 m² |
| 75mm |
6.7 m² |
13.3 m² |
| 100mm |
5 m² |
10 m² |
| 150mm |
3.3 m² |
6.7 m² |
Recommended depths by product
Allow for settling and compaction
The volume you order is measured loose. Once it's in place, most products settle:
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Garden mix, compost and lawn soil settle as they're watered and firmed. Add about 10–15%, especially when filling raised beds.
-
GAP20 and crusher dust compact down when you run a plate compactor over them. Add around 20–25% so you finish at the depth you planned.
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Bark and mulch settle a little in the first few weeks and break down over time. Most gardens need a top-up each year.
Raised bed example: a 2.4m × 1.2m bed filled 400mm deep holds 2.4 × 1.2 × 0.4 = 1.15 m³. Allowing for settling, order 1.5 m³ of Garden Mix, or 1 m³ of Garden Mix plus ½ m³ of Compost to blend through.
Irregular shapes
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Curved beds: break the area into rough rectangles, work out each one and add them up.
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Circles: 3.14 × radius × radius gives the area. A 2m-wide circle around a tree (1m radius) is about 3.1 m².
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Triangles: half of length × width.
When in doubt, round up to the next ½ m³. A small amount left over is always handy for topping up pots and patches.
Getting it home
Stone, sand and metal are heavy, roughly 1.5 tonnes or more per cubic metre, so even ½ m³ can be close to the limit of a standard box trailer. Soil and compost are lighter, and bark and mulch much lighter again. Check your trailer's rating before you load up, and ask the team at your local yard if you're unsure. For bigger jobs, our bulk packs are a tidy alternative you can load straight into a ute or van.
Quick answers
How much bark do I need for 10 m²? At 100mm deep, 1 m³ (two ½ m³ lots). At 75mm, about 0.75 m³, so order 1 m³.
How much garden mix fills a raised bed? Multiply length × width × depth in metres, then add 10–15% for settling.
Can I mix products in one trailer load? Ask at your local yard; it depends on the products and the yard.
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