How to use
A walkthrough of the calculator, from the tape measure to the order.
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Step 1: Measure the area
Measure the space in whatever unit is convenient and pick the matching shape. For an L shape or a garden bed with an odd corner, switch to the irregular option and enter each rectangle as its own section.
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Step 2: Set the depth
Depth is where most of the error lives, because it multiplies straight through to the tonnage. Two inches against three is a fifty percent difference in what you pay. Choose a project and the calculator suggests the depths that job usually runs at.
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Step 3: Pick the material, or your supplier's density
Each material carries a typical bulk density. If your supplier has quoted a figure, enter theirs instead: it describes the actual pile you are buying, which no published average can.
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Step 4: Add an allowance, then order
Add ten percent or so for spillage, uneven ground and settling. The result shows the exact figure, the figure with the allowance, and the amount rounded up to something the yard will sell. Share the link or print the summary to take with you.
Things worth knowing
Density is not a constant, so two yards will quote different tonnages for the same cubic yard. Loose gravel settles when it is compacted, which is why a compacted layer needs more material than its finished depth suggests. And if a supplier has a five ton minimum, that is what you are buying whether the job needs it or not.