Concrete Calculator
Cubic yards
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Cubic feet
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Add 10% extra for waste and spillage.
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How Much Concrete Do You Need?
Concrete volume is measured in cubic yards for ready-mix orders and cubic feet for bagged concrete. One cubic yard equals 27 cubic feet. Most DIY projects under 1 cubic yard use bags; larger jobs use ready-mix delivered by truck (typically ordered by the cubic yard).
Bags per Cubic Foot
Standard Concrete Depths
Frequently Asked Questions
Should I order extra concrete?
Always order or buy 10% more than calculated. Concrete is lost to spillage, uneven subgrade, and the waste inherent in mixing. Running short mid-pour causes cold joints — weak seams where fresh concrete meets partially set concrete — which can crack. It's much better to have a small amount left over.
When should I use ready-mix vs. bags?
For projects under about 0.5–1 cubic yard (13–27 cubic feet), bagged concrete is practical. Above that, ready-mix is faster, cheaper per yard, and ensures a consistent mix. Ready-mix trucks typically deliver a minimum of 1 cubic yard and charge extra for small loads. For a 10×10 ft slab at 4 inches, you need about 1.2 yards — right at the decision point.
What PSI should I use?
Standard residential concrete is 3,000–4,000 PSI. Driveways and garage floors typically use 4,000 PSI for durability. Sidewalks and patios are fine at 3,000–3,500 PSI. Structural foundations may require higher PSI — consult your local building code or an engineer.