Yards, Bags, or Tons: How Bulk Materials Are Actually Sold
CalcAnvil · updated August 2026
Bulk landscape material moves through three unit systems on its way to your project: your plan thinks in square feet and inches of depth, the supplier quotes cubic yards, and the truck that arrives was weighed in tons. Two of those conversions are exact. One is not, and knowing which is which saves arguments at the scale house.
The Exact Part: the 324 Rule
Cubic yards = square feet × depth in inches ÷ 324. That divisor works because a cubic yard is 27 cubic feet and an inch is a twelfth of a foot: 27 × 12 = 324. So one yard covers 324 square feet at one inch deep, 108 square feet at three inches, 54 at six. Bags are exact too, because a bag is a labeled volume: 13.5 two-cubic-foot bags make a yard, 27 one-cubic-foot bags, 54 half-cubic-foot bags. If a calculator disagrees with these numbers, the calculator is wrong.
The Inexact Part: What a Yard Weighs
Stone sells by the ton because trucks are weighed, and the volume-to-weight bridge runs through density, which is not one number. Gravel runs roughly 1.2 to 1.6 tons per cubic yard depending on stone type, gradation, and, above all, moisture: rain at the pit can move delivered weight 15 percent. Wood mulch barely registers at 0.3 to 0.5 tons per yard. Any site quoting exact tonnage for "gravel" chose a point inside that band without telling you. Our gravel calculator shows the band and names the density preset instead.
The Allowance People Forget: Compaction
Base material under pavers or a slab gets compacted, and compaction eats 10 to 20 percent of the loose volume. Order exactly the finished-depth volume and your compacted base lands short. This is a trade convention, not a published standard, and we label it that way, but it is the difference between one delivery and two.
The 324 rule per Texas AgriLife Extension; density bands per the mining-handbook figures cited on each calculator. Playground surfacing has its own depth rules (CPSC recommends 9 inches of loose-fill wood mulch): see the playground mulch calculator. Full sourcing on the methodology page.