calcs.homes
calcs.homes
Estimate cubic yards, bags, and cost for a concrete slab, footing, or column — this concrete calculator covers foundation pours, driveways, and formula-based estimates for any thickness.
Estimate only — actual needs vary with subgrade and mix. Confirm with your supplier.
We multiply length × width × thickness (or radius² × π × height for columns) to get cubic feet, add your waste factor, then divide by 27 to convert to cubic yards. Bag count divides that same volume by a bag's yield — about 0.45 cu ft for a 60 lb bag or 0.6 cu ft for an 80 lb bag — and rounds up, since suppliers only sell whole bags.
This is the same volume-first method ready-mix suppliers and contractors use to price a pour: cubic yards drive delivery quotes, while bag yield drives DIY bag counts. The 10% waste factor defaults on because uneven subgrade, spillage, and over-excavation reliably eat into a "clean" volume calculation — uncheck it only if you've already accounted for those losses elsewhere.
Materials alone typically run $110–$165 per cubic yard for ready-mix, or use the bag-price field above for a bagged-concrete DIY estimate. Add labor, forms, and rebar for a full foundation cost.
About 60 bags of 60 lb concrete, or 45 bags of 80 lb concrete, make one cubic yard (27 cu ft).
Uneven subgrade, spillage, and over-excavation typically use up an extra 5–10% of material. We default to 10% — uncheck the box to see the exact formula result.