A yard of concrete is the standard unit of measure used when ordering ready-mix concrete for construction projects. This term is an abbreviation for a cubic yard, which measures volume, not length. A cubic yard represents 27 cubic feet of material and is the universal quantity suppliers use to price and deliver concrete to a job site. Understanding this volume is the first step in accurately planning any project.
The Cubic Yard Defined
A cubic yard is a three-dimensional volume equivalent to a cube measuring three feet wide, three feet long, and three feet high (3′ x 3′ x 3′). It contains 27 cubic feet of material. The weight of this volume is considerable; a standard concrete mix typically weighing around 4,000 pounds per cubic yard, depending on the aggregate and moisture content. This weight is roughly equivalent to two small passenger cars, illustrating why proper subgrade preparation is necessary before pouring. For smaller projects, one cubic yard of concrete is enough to fill 18 to 20 standard wheelbarrows.
Calculating Your Concrete Needs
Determining the amount of concrete required involves converting the physical dimensions of the area into cubic yards. The calculation begins by measuring the length, width, and depth of the area to be filled, ensuring all measurements are in feet. Since slab depth is typically measured in inches, that measurement must be divided by 12 to convert it into a fraction of a foot. The formula for volume is (Length in feet $\times$ Width in feet $\times$ Depth in feet).
Once the volume in cubic feet is determined, divide that number by 27 to convert the total into cubic yards for ordering. For example, a 10-foot by 10-foot slab 4 inches deep is calculated as (10 ft $\times$ 10 ft $\times$ (4 in $\div$ 12)) $\div$ 27, resulting in approximately 1.24 cubic yards. This precision helps minimize waste and ensures enough material is on hand to complete the pour in one session.
It is advisable to add a buffer to the calculated volume to account for potential issues on the job site. The subgrade beneath the slab is rarely perfectly level, and some material may be lost to spillage or uneven forms. Adding a 5% to 10% contingency to the final calculation ensures there is enough concrete to fill the forms completely and avoid the delay of ordering a second delivery. This overage prevents the concrete from setting before the pour is finished.
Cost and Ordering
The price of a cubic yard of concrete is influenced by the mix design and delivery logistics. Standard ready-mix concrete typically costs between $120 and $175 per cubic yard, though this range can fluctuate based on regional market conditions.
A primary factor in the price is the concrete’s compressive strength, measured in pounds per square inch (PSI). A standard residential mix, such as 3,000 PSI for a sidewalk, is less expensive than a 4,000 PSI mix, which is required for driveways or foundations supporting heavier loads.
Specialized additives also increase the cost per yard by enhancing performance for specific applications. For instance, adding fiber mesh reinforcement improves crack resistance, while accelerators can speed up the curing process in cold weather. The distance from the supplier’s batch plant to the job site also affects the final price, as delivery fees are often calculated based on mileage beyond a certain radius.
When ordering from a ready-mix supplier, it is necessary to be aware of industry terms like “minimum load” and “short load fee.” Most suppliers operate with a minimum delivery volume, often between 5 and 7 cubic yards, to make the trip economically viable. If a project requires less than this minimum, a short load fee, which can range from $50 to over $100 per delivery, is typically applied to offset the cost of the partially filled truck.
Planning ahead is necessary, as suppliers often require a lead time of 24 to 48 hours, especially during peak construction seasons. Before the truck arrives, the site must be fully prepared. This means the forms are built, the subgrade is compacted, and any necessary reinforcement, such as rebar or wire mesh, is in place. Ensuring the site is ready prevents incurring waiting time charges, which can be billed by the minute if the pour is delayed.