Gravel Calculator

Volume is what you need, weight is what you buy

Area times depth gives cubic feet; divide by 27 for cubic yards. Suppliers then price by the ton, so the conversion runs through density. Crushed stone is around 1.4 tons per cubic yard, topsoil 1.2 and bark mulch only 0.4 — so the same hole takes three and a half times the tonnage in stone that it does in mulch.

Depth is where most jobs go wrong

Two inches of stone over soft ground disappears into the ground within a season. A driveway generally wants four to six inches of compacted stone over a prepared base; a garden path is fine with two to three. Because volume scales directly with depth, the difference between a two-inch and a four-inch spread is exactly double the order.

Compaction is not waste, but it costs the same

Loose aggregate compacts by roughly 10 to 20 per cent once rolled or driven on, so a four-inch finished depth needs more than four inches of loose material. The allowance above covers both compaction and ordinary spillage. Densities also vary with moisture content — wet sand can be 10 per cent heavier than the figure quoted here.

Compaction is why the delivered volume looks wrong

Crushed stone arrives loose and is installed compacted. Angular base material such as crusher run or dense-graded aggregate typically loses on the order of 20 to 25 per cent of its loose volume once it is properly compacted in lifts, so a bed that measures 4 inches deep after compaction needs closer to 5 inches of loose material delivered. Clean single-sized stone such as #57 barely compacts at all, because uniform round-ish particles have nowhere to migrate to, which makes it excellent drainage fill and poor structural base.

Weight conversions carry the same trap. Crushed stone runs roughly 1.3 to 1.5 tons per cubic yard depending on the rock and its moisture content, so a quote given in tons and a plan drawn in yards can differ by ten per cent purely through the density assumed. Where the number matters financially, ask the quarry for the density of the specific product being loaded rather than applying a generic figure, and order to the compacted depth plus the compaction allowance.

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