How the cubic yard calculation works
A cubic yard is a cube 3 ft on each side, so it holds 3 × 3 × 3 = 27 cubic feet. Bulk materials such as topsoil, gravel, mulch and ready-mix concrete are sold by the cubic yard in the US and often in Canada, and by the cubic meter in Australia and most other countries.
- Find the area. Length × width for a rectangle, or 3.1416 × (diameter ÷ 2)² for a circle.
- Convert the depth to feet. Depth is usually measured in inches, so divide by 12.
- Multiply area × depth to get cubic feet, then divide by 27 for cubic yards.
cubic yards = L (ft) × W (ft) × (depth in ÷ 12) ÷ 27
cubic meters = L (m) × W (m) × (depth cm ÷ 100)
Worked example
A bed 12 ft long and 10 ft wide, filled 4 in deep: 12 × 10 = 120 sq ft. 120 × (4 ÷ 12) = 40 cu ft. 40 ÷ 27 = 1.48 cubic yards, which is 1.13 m³. A round bed 10 ft across has an area of 78.5 sq ft; at 3 in deep that is 19.6 cu ft, or 0.73 cubic yards.
How far does one cubic yard go?
Turning the formula around tells you the area one cubic yard covers at a given depth: 324 ÷ depth in inches. In metric, one cubic meter covers 1 ÷ depth in meters.
| Depth | One cubic yard covers | Metric depth | One m³ covers |
|---|---|---|---|
| 1 in | 324 sq ft | 25 mm | 40 m² |
| 2 in | 162 sq ft | 50 mm | 20 m² |
| 3 in | 108 sq ft | 75 mm | 13.3 m² |
| 4 in | 81 sq ft | 100 mm | 10 m² |
| 6 in | 54 sq ft | 150 mm | 6.7 m² |
| 12 in | 27 sq ft | 300 mm | 3.3 m² |
Measuring tips
- Measure depth in several spots and use the average. Ground that looks flat often varies by an inch or more.
- Convert inches to decimal feet before multiplying: 6 in is 0.5 ft, 3 in is 0.25 ft. Mixing feet and inches in one sum is the most common error.
- Split L-shaped or irregular areas into rectangles and circles, work out each one, and add the volumes.
- For a half-circle, work out the full circle and halve it.
Typical depths for common materials
| Material and use | Common depth (rule of thumb) |
|---|---|
| Mulch on garden beds | 2 to 3 in (50 to 75 mm) |
| Topsoil to level or top-dress a lawn | 1/4 to 1/2 in for top-dressing; 4 to 6 in for new lawns |
| Gravel path or decorative stone | 2 to 4 in (50 to 100 mm) |
| Concrete patio or shed base | 4 in (100 mm) |
| Raised garden bed fill | the full height of the bed |
Depths for structural work such as driveways and footings depend on soil, loads and local code, so treat these only as starting points.
Order a little more than the math says
The result is the exact geometric volume. Real jobs need more. Loose material settles and compacts, uneven ground swallows extra, and some is always lost on the tarp or in the wheelbarrow. As a rule of thumb, add about 5 to 10 percent for mulch and soil, and 10 percent or more for gravel that will be compacted. Many yards and ready-mix plants sell in steps of a half or a quarter yard, so round up to the next step.
Cubic yards, tons and bags
Some suppliers sell stone and sand by the ton instead of by volume. Weight per cubic yard depends on the material and how wet it is, so convert with the supplier's own figure. The guide on how many tons are in a cubic yard gives typical rules of thumb. For bagged products, check the volume printed on the bag: there are 27 one-cubic-foot bags, or 13.5 two-cubic-foot bags, in a cubic yard.
For specific jobs, the concrete calculator, gravel calculator and mulch calculator add waste and bag counts for you.
Frequently asked questions
How many cubic feet are in a cubic yard?
27. A cubic yard is 3 ft × 3 ft × 3 ft. To convert cubic feet to cubic yards, divide by 27.
How do I convert cubic yards to cubic meters?
Multiply by 0.7646. One cubic meter is about 1.31 cubic yards.
How many square feet does a cubic yard cover?
Divide 324 by the depth in inches. At 3 in deep a cubic yard covers 108 sq ft; at 4 in it covers 81 sq ft.
How many cubic yards do I need for a 20 × 10 area 3 inches deep?
20 × 10 × 0.25 = 50 cubic feet, which is 1.85 cubic yards before any extra for settling.