What is a cubic yard?
A cubic yard is a volume measuring one yard long, one yard wide and one yard high. Because one yard equals three feet, one cubic yard contains 27 cubic feet.
Cubic yard formula
When length, width and depth are all measured in feet, multiply them to find cubic feet, then divide by 27.
When depth is measured in inches
Depth for mulch, gravel and similar materials is often specified in inches. Divide the depth by 12 to convert it to feet first.
Example: gravel area
For an area 30 feet long, 12 feet wide and 4 inches deep, convert 4 inches to approximately 0.333 feet. The volume is about 120 cubic feet, or approximately 4.44 cubic yards.
Why material quantities can differ from calculated volume
- Compaction can reduce final material depth.
- Loose material can settle after placement.
- Excavated surfaces are rarely perfectly level.
- Different materials have different densities and moisture content.
Cubic yards vs tons
Cubic yards measure volume while tons measure weight. Converting between them requires the density of the specific material. Gravel, soil, mulch and concrete do not share one universal conversion factor.
Supplier density, compaction assumptions and minimum delivery quantities can affect the amount you should order. Use the calculator as a planning estimate and confirm material-specific details with the supplier.
Worked example: cubic yards from feet
Suppose an area is 18 feet long, 10 feet wide and 6 inches deep. Convert 6 inches to 0.5 foot, then multiply 18 × 10 × 0.5 to get 90 cubic feet. Because one cubic yard contains 27 cubic feet, divide 90 by 27. The result is about 3.33 cubic yards before adding any project-specific allowance.
Depth is often the measurement that causes errors
Length and width are commonly measured in feet while material depth is entered in inches. Those units cannot be multiplied directly. Convert the depth to feet first, or use a calculator that handles the conversion automatically. For example, 3 inches is 0.25 foot, 6 inches is 0.5 foot and 9 inches is 0.75 foot.
Loose, compacted and finished volumes may differ
The geometric calculation tells you how much space the material must fill. Materials such as gravel, soil and mulch can settle or compact, so the quantity delivered may not behave exactly like a rigid geometric volume. When buying material, consider whether the supplier quotes loose volume, compacted volume, weight or another measurement basis.
When to calculate sections separately
Irregular projects are usually easier to estimate by splitting them into simpler rectangles. Calculate the cubic yards for each section using its own length, width and depth, then add the results. This is especially useful for driveways with extensions, landscaped beds with varying depth, and projects containing several material zones.