Concrete Calculator
Estimate concrete for a slab, patio, footing pad or other rectangular pour. Enter the slab dimensions and thickness, then add a small allowance for grade variation, spillage and measurement error.
Enter project details
Planning estimate only. Confirm local prices, supplier specifications and site conditions before ordering.
Your estimate
Concrete yield, minimum delivery quantities and local ready-mix pricing vary. Verify the final order with the supplier, especially for structural or time-sensitive pours.
Request local project quotes
Tell us about your concrete flatwork project. ProjectMetrica uses WiserLeads, the Triares/homeyou lead platform, to check whether a participating buyer is available for your project.
- No purchase is required.
- Availability and matching depend on ZIP code and project details.
- ProjectMetrica may receive compensation for a qualifying accepted request.
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How the concrete calculator works
Concrete volume = length × width × thickness. Thickness is converted from inches to feet, waste is applied, and cubic feet are converted to cubic yards. Bags = cubic feet ÷ bag yield.
For a better estimate
- Measure the actual pour thickness rather than the excavation depth.
- Concrete bag yields vary by bag weight and product, so use the yield printed on the bag.
- Ready-mix orders may have minimum-load, short-load and delivery charges that are not included here.
Tools that can help with this project
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Frequently asked questions
How many yards of concrete do I need?+
Multiply length by width by thickness in feet, then divide cubic feet by 27. Add a small allowance before ordering.
How many bags of concrete do I need?+
Divide the required cubic feet by the actual yield per bag. The calculator rounds bag quantities up to a whole bag.
Should I order extra concrete?+
A modest allowance can cover uneven subgrade, form variation and spillage. Large or structural pours should be verified carefully before ordering.