Cubic feet
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Round Concrete Slab Calculator
Round Concrete Slab calculator
Calculate concrete for round slabs, circular pads and patios. Cubic yards, bags, ready-mix loads and weight — with a waste margin built in, nothing leaves your browser.
Dimensions
FIG. 01Volume ÷ 27 = cubic yards. Pros order to the nearest ½ yard and add a waste margin — running short mid-pour risks a cold joint.
You need
—cu yd
Order to nearest ½ yd → — · —
Cubic meters
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80 lb bags
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60 lb bags
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Est. weight
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Best buy
see above
How this is calculated
A round slab is π × radius² × thickness. For a 10 ft diameter pad at 4 inches, that's about 26 cubic feet, or roughly 1 cubic yard. Enter the diameter (not radius) and the calculator does the rest.
cubic yards = volume in cubic feet ÷ 27 × (1 + waste%)
For the full method and sources, see the methodology page. Comparing buying options? Use the bags-vs-ready-mix calculator.
FAQ
How do I calculate concrete for a round slab?
A round slab is π × radius² × thickness. For a 10 ft diameter pad at 4 inches, that's about 26 cubic feet, or roughly 1 cubic yard. Enter the diameter (not radius) and the calculator does the rest.
How is a round slab different from a square one?
Only the area formula changes — circles use π·r² instead of length × width. A round pad uses about 21% less concrete than the square slab that would enclose it, so don't estimate it as a square.