Coverage per cubic yard at common depths
Because volume is fixed at 27 cubic feet per cubic yard, the area one cubic yard covers falls as the pour gets thicker — useful for a quick sanity check against a quoted delivery.
| Depth | Area covered by 1 cubic yard |
|---|---|
| 2 in | 162 sq ft |
| 3 in | 108 sq ft |
| 4 in | 81 sq ft |
| 6 in | 54 sq ft |
| 8 in | 40.5 sq ft |
- Ready-mix concrete suppliers commonly apply a minimum order (often around 1 cubic yard) and may charge a short-load fee below that threshold — check with the supplier before ordering a small quantity.
- A waste allowance (commonly 5-10%) accounts for subgrade irregularities, spillage and overfill; this calculator applies 10% as a standard default that can be adjusted for the specific site.
What is a cubic yard, and why does it matter for ordering material?
A cubic yard is a volume equal to a cube 3 feet (1 yard) on each side — 27 cubic feet. In the US, bulk materials such as ready-mix concrete, gravel, topsoil, sand and mulch are conventionally priced and delivered by the cubic yard, which is why converting an area and depth into cubic yards is the first step in ordering any of these materials.
Because delivered volume is what you pay for, small measurement errors compound quickly over a large area — this calculator standardizes the length-width-depth-to-volume conversion so the ordering quantity matches what the job actually needs.
How to use this cubic yard calculator
- Enter the length of the area in feet.
- Enter the width of the area in feet.
- Enter the depth (or slab thickness) in inches.
- Read the volume in cubic yards, cubic feet and cubic meters, plus a suggested order volume with a 10% waste allowance for spillage, overfill and subgrade irregularities.
The formula behind cubic yards
Volume in cubic feet equals length (feet) multiplied by width (feet) multiplied by depth (feet); because depth is usually measured in inches, it is first divided by 12 to convert to feet. Cubic yards equal cubic feet divided by 27, since a cubic yard contains exactly 27 cubic feet (3 ft × 3 ft × 3 ft).
Worked example: a 20 ft × 15 ft slab area at a 4-inch depth gives 20 × 15 × (4 ÷ 12) = 100 cubic feet, which is 100 ÷ 27 ≈ 3.70 cubic yards. This also means one cubic yard of concrete at a 4-inch depth covers about 81 square feet (27 ft³ ÷ (4/12 ft) = 81 sq ft).
Common mistakes
- Entering depth in feet instead of inches (or vice versa), which throws the volume off by a factor of 12.
- Confusing cubic yards (a volume) with square yards (an area) when discussing a delivery quantity.
- Ordering the exact calculated volume with no waste allowance, then coming up short mid-pour.
- Not accounting for a supplier's minimum order or short-load fee when the calculated volume is small.
Domande frequenti
How many cubic feet are in a cubic yard?
One cubic yard equals 27 cubic feet, since a cubic yard is a cube 3 feet on each side (3 × 3 × 3 = 27).
How do I convert square feet to cubic yards?
Multiply the square footage by the depth in feet to get cubic feet, then divide by 27. For a 4-inch depth (1/3 ft), 300 sq ft × 0.333 ft = 100 ft³, which is 100 ÷ 27 ≈ 3.70 cubic yards.
How much concrete does one cubic yard cover?
At a 4-inch slab depth, one cubic yard of concrete covers about 81 square feet; coverage increases at shallower depths and decreases at deeper ones, since volume per yard is fixed at 27 cubic feet.
Should I order extra material beyond the calculated volume?
Yes — a waste allowance of roughly 5-10% is standard practice to cover subgrade irregularities, spillage and minor measurement error; this calculator applies a 10% allowance by default.
How do cubic yards convert to cubic meters?
Multiply cubic feet by 0.0283168 to get cubic meters, or multiply cubic yards by about 0.7646; a 3.70 cubic yard order is roughly 2.83 cubic meters.
Fonti
- National Ready Mixed Concrete Association (NRMCA) — concrete ordering and delivery is conventionally by the cubic yard in the US.
- NIST Handbook 44 / standard US customary unit definitions — cubic yard as 27 cubic feet.
- American Concrete Institute (ACI) — general slab thickness and ordering-margin practice for flatwork.