Landscaping
Bulk materials are sold by the cubic yard and spread by the inch. The table below converts between the two, and the calculators do the rest.
- Gravel Calculator
Enter the area and the compacted depth to get the volume of gravel in cubic yards — the unit aggregate is actually sold in.
- Topsoil Calculator
Enter the area and the settled depth to get the volume of topsoil in cubic yards — the unit it is sold and delivered in.
What one cubic yard covers, by depth
| Depth | Coverage per cubic yard | Cubic yards per 100 sq ft |
|---|---|---|
| 1 in | 324 sq ft | 0.31 |
| 2 in | 162 sq ft | 0.62 |
| 3 in | 108 sq ft | 0.93 |
| 4 in | 81 sq ft | 1.23 |
| 6 in | 54 sq ft | 1.85 |
Arithmetic, not a material property: one cubic yard is 27 cubic feet by definition, so coverage is 27 divided by the depth in feet. It holds for gravel, topsoil, mulch, sand or anything else spread to a depth.
Source: Volume unit definitions: 1 cubic yard = 27 cubic feet; 1 ft = 0.3048 m
Depth is the number that moves the answer
Length and width get measured carefully and depth gets guessed, which is backwards. Doubling the depth doubles the material; being an inch out across 600 square feet is nearly two cubic yards.
The table above is the one to keep. It says nothing about the material — it is pure arithmetic on the definition of a cubic yard — which is why it holds for whatever you are spreading.
Compacted, settled, or loose
Bulk materials are quoted loose and used compacted or settled, and the two numbers differ by enough to matter.
Aggregate loses roughly a fifth of its loose volume when it is plate-compacted. Screened topsoil settles by something like a tenth once it is watered in. Both of these are judgement calls that depend on the material and how hard you work it, so the calculators take them as an allowance you enter rather than assuming a figure on your behalf.
Yards, not tons
Both calculators here report cubic yards, because that is the unit these materials are ordered and delivered in. Some suppliers quote by the ton instead, and the conversion varies by product, quarry and moisture content — enough that publishing a single figure would be inventing one. Ask the supplier for the conversion for the specific material, and compare quotes in the same unit.