Before you order sand, soil, gravel or mulch, you need one number: how much material your job actually needs. Order short and you’re back for a second delivery. Order long and you’ve paid for a pile that sits in the yard. This guide gives you the simple maths, a coverage table for every material family we stock, and the common spread depths by job so you can get close in under a minute. For an exact figure and a delivered price to your suburb, drop your measurements into our material calculator.
The one formula that covers everything
Every quantity job comes down to volume, then weight:
- Area (m²) × depth (m) = volume (m³)
- Volume (m³) × density (t/m³) = weight (tonnes)
Two things trip people up. First, depth is in metres, not millimetres: a 50mm layer is 0.05m, 75mm is 0.075m, 100mm is 0.1m. Second, every material weighs a different amount per cubic metre, so a tonne of mulch goes a lot further than a tonne of road base.
A worked example. Say you’re topping a garden bed 6m × 4m with 75mm of soil:
- Area = 6 × 4 = 24 m²
- Volume = 24 × 0.075 = 1.8 m³
- Weight = 1.8 × 1.3 (soil density) = 2.34 tonnes
So you’d order roughly 2.5 tonnes, or a 1.5t plus a 1t bulka bag if you’d rather bag than loose. That’s the whole method. The tables below just save you doing it by hand.
Densities we work to
These are the working densities we use across the yard. They’re close enough for ordering; natural materials vary a little with moisture and compaction.
| Material family | Density (t/m³) | 1 tonne = |
|---|---|---|
| Sand & decorative pebbles | 1.5 | 0.67 m³ |
| Road base & blue metal (gravel) | 1.6 | 0.63 m³ |
| Soil & garden mixes | 1.3 | 0.77 m³ |
| Mulch | 0.5 | 2.0 m³ |
Notice mulch: because it’s light, one tonne is a full 2 cubic metres, which is why mulch is often sold and thought about by the cubic metre rather than the tonne.
Coverage by material: how far a tonne goes
Each table shows roughly how many square metres one tonne covers at common spread depths. Find your material, pick your depth, read across.
Sand (paving, bedding, brickies)
Density 1.5 t/m³. Bedding sand under pavers usually goes 25–30mm; sand as a base under turf or a slab, more like 50mm.
| Depth | m² per tonne | m² per m³ |
|---|---|---|
| 25mm | ~26.7 m² | 40 m² |
| 50mm | ~13.3 m² | 20 m² |
| 75mm | ~8.9 m² | 13.3 m² |
Not sure which sand? Washed river sand suits concrete and general work, kiln-dried sand sweeps into paver joints, and USGA sand is the spec for turf construction. Our which sand do I need guide walks through the lot.
Gravel & road base (driveways, base layers, drainage)
Density 1.6 t/m³. Road base for a driveway is typically laid 100mm compacted; decorative blue metal over a base or in drainage trenches sits around 50mm.
| Depth | m² per tonne | m² per m³ |
|---|---|---|
| 50mm | ~12.5 m² | 20 m² |
| 75mm | ~8.3 m² | 13.3 m² |
| 100mm | ~6.3 m² | 10 m² |
For driveways and pads, recycled road base (DGB20) compacts hard and is the value pick; our DGB20 road base guide covers depths and compaction. For decorative and drainage stone, compare 10mm blue metal and 20mm blue metal, or read 10mm vs 20mm blue metal to pick the right size.
Soil & garden mixes (beds, veggie patches, top dressing)
Density 1.3 t/m³. New garden beds usually want 200–300mm of soil (build it in layers); a top-dress over an existing bed or lawn is 25–50mm.
| Depth | m² per tonne | m² per m³ |
|---|---|---|
| 25mm | ~30.8 m² | 40 m² |
| 50mm | ~15.4 m² | 20 m² |
| 100mm | ~7.7 m² | 10 m² |
For lawns, a fine screened soil spread thin is the trick; see our lawn top dressing guide. Building beds or levelling, our exclusive Elite 80/20 sand-soil blend is a Sydney favourite for its drainage and structure.
Mulch (garden beds, playgrounds, moisture retention)
Density 0.5 t/m³, so it goes twice as far as sand per tonne. Garden mulch is laid 50–75mm; certified softfall under play equipment goes much deeper, commonly 200–300mm to meet the fall-height rating.
| Depth | m² per tonne | m² per m³ |
|---|---|---|
| 50mm | ~40 m² | 20 m² |
| 75mm | ~26.7 m² | 13.3 m² |
| 100mm | ~20 m² | 10 m² |
For play areas, softfall mulch is the certified product; for garden beds, our which mulch to use guide helps you match colour, longevity and price.
Decorative pebbles (feature beds, paths, pots)
Density around 1.5 t/m³, same as sand. Pebbles as a decorative topping usually go 40–50mm so the ground doesn’t show through; over weed matting, 50mm is the safe minimum.
| Depth | m² per tonne | m² per m³ |
|---|---|---|
| 25mm | ~26.7 m² | 40 m² |
| 50mm | ~13.3 m² | 20 m² |
| 75mm | ~8.9 m² | 13.3 m² |
A tidy white pebble like Cowra White 20mm lifts a feature bed instantly. For sizes, colours and coverage tips, see our decorative pebbles guide.
Common spread depths by job
If you’re not sure how deep to go, start here. These are the depths most jobs use before compaction.
| Job | Material | Typical depth |
|---|---|---|
| Paver bedding | Bedding sand | 25–30mm |
| Driveway base | Road base (DGB20) | 100mm compacted |
| Decorative stone / drainage | Blue metal | 50mm |
| New garden bed | Soil / garden mix | 200–300mm |
| Lawn top dressing | Fine screened soil | 10–25mm |
| Garden mulch | Mulch | 50–75mm |
| Playground softfall | Softfall mulch | 200–300mm |
| Pebble topping | Decorative pebbles | 40–50mm |
Loose, bulka bag or pickup: how it ships
Once you know your tonnage, you’ve got three ways to get it. We deliver loose from 500kg across Sydney on our own 60-plus truck fleet, so you’re not waiting on a third-party carrier. Prefer it bagged? We supply bulka bags in 1 tonne and 1.5 tonne sizes, handy for tight access or when you want the material kept off the driveway. Or pick up yourself at the Jamisontown yard. If your figure lands between sizes, round up: a little spare beats a second trip.
A note on asphalt
People often ask us to quantify asphalt off a coverage table too. We keep small buckets of cold-mix asphalt on the shelf for potholes and patch repairs, ready to grab and go. For larger quantities we arrange asphalt as a special order, so give us a call on 1300 935 483 with your area and we’ll sort the right amount.
Get the exact number (and the delivered price)
The tables above get you close, which is fine for a rough order. For an exact figure to the tonne, plus what it costs delivered to your suburb, use the material calculator. Punch in your length, width and depth, pick your material, and it does the volume-and-density maths in one go. It’s the fastest way to turn a garden bed into a confident order.
FAQ
How many square metres does a tonne cover?
It depends on the material and the depth. As a rule of thumb at 50mm: sand or pebbles cover about 13 m² per tonne, road base about 12.5 m², soil about 15 m², and mulch about 40 m² per tonne because it’s much lighter. Use the material calculator for your exact depth.
How do I convert cubic metres to tonnes?
Multiply cubic metres by the material’s density: sand and pebbles ×1.5, road base ×1.6, soil ×1.3, mulch ×0.5. So 2 m³ of soil is 2 × 1.3 = 2.6 tonnes.
How deep should I lay each material?
Bedding sand goes 25–30mm, driveway road base 100mm compacted, garden mulch 50–75mm, playground softfall 200–300mm, and pebble toppings 40–50mm. New garden beds usually want 200–300mm of soil built up in layers.
What’s the minimum I can order?
We deliver loose from 500kg across Sydney. You can also order bulka bags in 1 tonne and 1.5 tonne sizes, or pick up any quantity yourself from the Jamisontown yard.
Should I round up or down when ordering?
Round up. Materials settle and compact, spread is never perfectly even, and a small amount spare costs far less than a second delivery. If you’re between bag sizes, take the larger one.
Still not sure how much you need? Run your measurements through the material calculator for an exact tonnage and delivered price, call the yard on 1300 935 483, or pop in and see us at 4 Harford St, Jamisontown. We’re open six days.