Gravel Calculator NZ

This calculator works out how much gravel, metal or aggregate to order for a driveway, path, base course or drainage layer, so you can buy close to the right amount instead of guessing and either running short mid-job or paying for material you never use. You enter the area you need to cover in square metres, the depth you want to lay it in millimetres, and the density of the material in tonnes per cubic metre, which defaults to 1.5 but can be changed to match the figure your quarry or landscape supplier gives you for the specific gravel, metal or aggregate you are buying. From those three figures the calculator instantly returns the volume in cubic metres and the total weight in tonnes, which is how most New Zealand suppliers price and deliver bulk gravel. Because paths and driveways are rarely a single neat rectangle, measure and add up the area of each section separately before you enter a total, and remember that a driveway base is usually laid deeper than a garden path. It is also worth ordering a bit extra beyond the calculated figure, since gravel compacts and settles once it is spread, driven on and rained on, so the finished depth ends up shallower than what you first laid. These are quantity estimates only; always confirm final volumes with your supplier before ordering.

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Order a little extra to allow for compaction and settling.