Calculate material quantity.

What this calculator works out

This tool converts an area and a depth into a volume, then translates that volume into something more useful when you're actually ordering: an approximate number of 25-litre bags for small jobs, or bulk truckloads for larger ones. It covers four common landscape materials — mulch, topsoil, aggregate and turf underlay sand — each with a sensible default depth you can adjust.

Getting the depth right matters more than most people expect. Too shallow and mulch fails to suppress weeds or topsoil doesn't give new planting enough root run; too deep and you're paying for material and delivery you didn't need. The default depths here reflect typical practice for each material, but site-specific advice can vary that.

Volume scales directly with both area and depth, so doubling either roughly doubles the material required — useful to know if you're deciding whether to cover a whole bed now or start with a smaller area and expand later. Bagged material suits small areas or top-ups where delivery access is limited; bulk truckloads are almost always cheaper per cubic metre for larger areas, but need somewhere for the load to be tipped or a wheelbarrow run to move it from the drop point.

This estimate covers material only — it does not include delivery, spreading labour, or site preparation such as removing existing groundcover or improving drainage before topsoil goes down. Ordering slightly more than the calculated volume is sensible for uneven ground or settling, particularly with loose materials like mulch.

Depth requirements can also depend on what the material is doing — mulch for weed suppression needs less depth than mulch also intended to insulate plant roots over winter, and topsoil for a new lawn needs more depth than topsoil for topping up an established bed. Adjust the depth field if your situation doesn't match the default.

Costs quoted per cubic metre also vary by supplier and region, so the figure here is a general guide rather than a specific supplier's price list — use it to compare options, not to hold any one supplier to an exact quoted number.