The base is what keeps paving flat. Nearly every wavy patio is a base problem being blamed on the sand, and the fix costs less than the repair — more base, less bedding. This works out the depth and the quantity, and tells you when bags stop being sensible.
The compacted aggregate layer under block paving, flags and slabs. Pick what will use the surface, then enter the paved area.
Works in metric and US imperial — you choose at the start and can switch at any time. Every figure this calculator uses is published with its source, and the result comes with a printable order sheet. No account, no email, and nothing you type leaves your browser.
Related: Paver sand calculator · Crusher run calculator · #57 stone calculator
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The base is what keeps paving flat. Nearly every wavy patio is a base problem being blamed on the sand, and the fix costs less than the repair. Pick what will use the surface and the calculator sets the depth — around 100 mm compacted for a patio, path or sidewalk, 150 mm for a residential driveway — then adds 25% so the loose figure you order finishes at the depth you asked for.
Extend it at least 150 mm / 6 in beyond the edge on every side. Paving fails from its edges inward, and an edge restraint sitting on soil rather than on base is the mechanism. So measure the base area as the paved area plus that margin all round — on a 4 × 5 m patio it is the difference between 20 m² and 22.4 m², which is a real quarter-tonne of stone.
Proprietary bagged paver base is dense-graded aggregate — the same material any yard sells loose as crusher run, at several times the price. Convenience is the only thing being sold. And do not use clean stone: #57 and other washed, open-graded stone will not lock up, so the paving above it moves. Clean stone is right for a permeable build and wrong under conventional paving.
About 100 mm compacted for a patio, path or sidewalk, and 150 mm for a residential driveway, over ground that drains. Compact in 75–100 mm layers — a 150 mm base is two lifts, because a plate compactor cannot work through more than about 100 mm of loose material.
Yes, by at least 150 mm (6 in) on every side. Paving fails from its edges inward, and an edge restraint sitting on soil rather than on compacted base is the usual reason.
Rarely. It is dense-graded aggregate — the material a yard sells loose as crusher run — at several times the price. For anything larger than a couple of square metres, buy it loose.
Not under conventional paving. Clean, open-graded stone will not lock up, so the paving above it moves. It is the correct material for a permeable build, where the whole point is that water passes through, but not otherwise.