Use this concrete calculator to estimate a pour before you order ready-mix or buy premix bags. Enter the project shape, dimensions, quantity, and overage. The calculator returns cubic yards, cubic feet, cubic meters, rounded-up bag counts, estimated weight, and optional material cost. If you already have bags on hand, switch modes to see how much slab area they can cover at your chosen thickness.
Turn the concrete result into an order check
Before buying bags or calling a ready-mix supplier, use these checks to make sure the estimate matches the actual pour conditions and ordering constraints.
Confirm the geometry
Measure the formed area after excavation and base preparation, not just the plan dimensions. Uneven subgrade depth, thickened edges, and repeated post holes can change the cubic-yard result enough to matter at order time.
Match the buying method
Use ready-mix pricing when you are ordering by the cubic yard and bag pricing when you plan to buy premix. Compare the material subtotal with delivery fees, minimum-load charges, equipment rental, and the labor needed to place the concrete before it sets.
Frequently asked questions
How do I calculate cubic yards of concrete?
Multiply the length, width, and thickness of your slab together, with all three dimensions in feet. Divide that product by 27 to convert cubic feet to cubic yards.
What is the formula for calculating concrete volume?
The formula is length times width times thickness, all measured in feet, then divided by 27 for cubic yards. Once you know your yardage, you can price the job. In 2026, delivered ready-mix runs roughly 150 to 200 per cubic yard, depending on your region.
How do I convert inches to feet for concrete thickness?
Divide your thickness in inches by 12 to get feet. A 4-inch slab is 0.33 ; 6 is 0.50 . Any pour over 1 — roughly 45 eighty-pound bags — is easier and cheaper to order as ready-mix.
How much concrete do I need for my project?
Find your volume by multiplying length by width by thickness in feet, then divide by 27. A common 20-by-20-foot slab at 4 thick needs about 5 . With concrete, labor, and base prep included, expect to pay 3,500 to 6,000 all in for that size.
How do I calculate cubic yards when my measurements include both feet and inches?
Convert any inch measurements to feet by dividing by 12, then multiply length by width by thickness. Divide the total cubic feet by 27 to get cubic yards. For example, 10 poured at 4 thick covers about 810 , showing how the math scales.