One of the questions I’m asked most often at Wellington Sand & Gravel is, “How much soil, sand, gravel or mulch do I need?”

It’s a good question because ordering the right quantity can save you time, money and an extra trip halfway through the job. While every site is different, a few simple measurements will give us a good starting point.

Working Out Cubic Metres
Most landscaping materials are measured and sold by the cubic metre. To estimate what you need, use this formula: Length × Width × Depth = Cubic Metres

Make sure all your measurements are converted into metres before you calculate the total. For example, let’s say your garden bed is 5 metres long and 2 metres wide, and you want to spread mulch 100mm deep: 5m × 2m × 0.1m = 1 cubic metre

Here are some common depth conversions:
50mm = 0.05m
75mm = 0.075m
100mm = 0.1m
150mm = 0.15m

How Deep Should the Material Be?

• The right depth will depend on the product, the condition of your site and what you’re trying to achieve.
• Mulch is generally applied at around 50–75mm deep. This provides good coverage while helping retain moisture and suppress weeds.
• Topsoil and garden mix can be used for everything from lightly top dressing a lawn to filling new garden beds, so the required depth can vary considerably.
• Gravel, road base and crusher dust may need to be laid deeper, particularly for driveways, shed pads and areas that will be compacted or carry vehicles.
• Sand will also vary depending on whether it’s being used for paving, top dressing, a sandpit or another project.

Allow for Compaction and Uneven Ground
Calculating the area gives you a useful estimate, but I generally recommend allowing a little extra. Ground is rarely perfectly level, and products such as road base and crusher dust will settle once they are spread and compacted.

The amount of extra material you’ll need depends on the product and the job, so it’s worth speaking with us before placing your order.

Still Not Sure? Give Me a Call

You don’t need to work it all out alone. Measure the approximate length, width and required depth of the area, then give me a call. I can help you estimate the quantity, select the right product and discuss pickup or delivery.

Call Wellington Sand & Gravel on 0488 753 311 and we’ll help get your project sorted.

Jamie Sattler
Wellington Sand & Gravel