Concrete calculator
Enter slab length, width, and thickness, pick a QUIKRETE bag weight, and read cubic yards plus bag counts. One table lists the same footprint at three through six inch thicknesses with forty, sixty, and eighty pound yields. Optional overage is trade convention, not a standard, with a visible footnote. Share links keep dimensions after the hash only.
Slab dimensions
Thickness series
Waiting for slab dimensions.
QUIKRETE publishes that all yields are approximate. Home improvement retailers carry similar disclaimers that calculations are estimates only. This page rounds bag counts up, never down, and shows leftover volume explicitly.
- Cubic yards
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- Bags
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- Leftover
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- Requests
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- Script
- · KB of a 100 KB budget
One job, one page
Search already answers generic head terms like "concrete calculator" with supplier pages. This page targets the job of ordering bags for a slab: length, width, thickness, and a bag weight you can buy at the store.
A 10 by 10 slab at four inches
Ten feet by ten feet by four inches is 1.235 cubic yards. Using the QUIKRETE 1101 yield of 0.60 ft³ per 80 lb bag, that is 56 bags before overage, and the leftover line shows the unused fraction of the last bag because counts round up, never down. Change thickness to five inches in the series table and the 80 lb column moves without retyping the footprint. That table is the reason this is not a generic "material calculator" with the noun swapped: mulch is volume of a bed, flooring is boxes of a coverage, and this page is bags of a slab.
Four inches is the common patio starting point, not a governing number. Load, sub-base, and the local building department decide thickness. How thick should a concrete patio slab be states what that four-inch convention assumes, and sends you to your building department rather than publishing a thickness as if it governed.
Why a series table
Thickness is the variable most people are still deciding. The table repeats the same footprint at three, four, five, and six inches so you can compare bag counts without retyping dimensions. Forty, sixty, and eighty pound columns use QUIKRETE 1101 yields cited on the page.
What this page will not compute
Footings, columns, circular slabs, curbs, and stairs are out. So is a country-by-country bag-yield table: the numbers here are QUIKRETE 1101, with Sakrete's 45 bags per cubic yard as a check on the eighty pound column, not a second product line. Ready-mix truck ordering is a different unit. This version ships rectangular slab first.
Questions
Where do the bag yields come from?
From the QUIKRETE 1101 data sheet: about 0.30 ft³ per 40 lb bag, 0.45 for 60 lb, 0.60 for 80 lb, and 0.675 for 90 lb. The eighty pound bag count per cubic yard matches Sakrete's published 45 bags figure.
Is the ten percent overage a standard?
No. Sakrete recommends adding about ten percent as a trade convention, and NRMCA Concrete in Practice does not publish a numeric ready-mix ordering overage figure. The field is optional and labeled accordingly.
Are my dimensions uploaded?
No. Calculations run in this tab. A share link stores your inputs after the hash mark, which browsers do not send with the page request.
Related tools
Thickness is not a bag-count question: how thick should a concrete patio slab be is the matching explainer. More material calculators live on the home project tools hub, including the mulch calculator and the flooring calculator.