Updated July 18, 2026
The numbers this calculator uses
| Constant | Value used here | Source |
|---|---|---|
| 60 lb bag yield | 0.45 ft³ per bag | Quikrete Concrete Mix data sheet |
| 80 lb bag yield | 0.60 ft³ per bag | Quikrete Concrete Mix data sheet |
| Cubic feet per cubic yard | 27 (fixed geometry) | n/a |
| Ready-mix truck load | 10 cubic yards per truck | Used by this calculator; truck capacity varies by mixer and hauler, so treat this as a planning round number, not a spec |
| Default waste factor | 10% (you can change it) | Editorial default, not a cited figure |
How it works
Volume = length × width × thickness, converted to cubic yards (÷ 27). We then convert to bags using the yields above and to truck loads at 10 yd³ per ready-mix truck.
The bag yields above come straight from Quikrete's own data sheet, and the pricing further down tracks HomeGuide's contractor cost survey. See how we pick sources on the editorial standards page.
What actually gets delivered
A cubic yard of concrete is 27 cubic feet, and it takes 45 eighty-pound bags or 60 sixty-pound bags to fill that yard. For a poured job, work out your volume first, then decide whether bags or a ready-mix truck makes more sense. Most slabs under a yard are a bag job. Anything bigger usually goes to ready-mix.
Doing the math by hand
Volume is length times width times thickness, with thickness converted from inches to feet. Take a 10 by 10 foot slab poured 4 inches thick. Four inches is 0.333 feet, so the math is 10 x 10 x 0.333, which gives 33.3 cubic feet. Divide by 27 and you get 1.23 cubic yards. To turn that into bags, divide the cubic feet by the bag yield: 33.3 divided by 0.60 is 56 eighty-pound bags, and 33.3 divided by 0.45 is 74 sixty-pound bags. Always round up to whole bags, because you cannot buy half a bag and you will spill some.
How to measure the pour
Measure length and width at the widest points and write them down. Set your thickness from the job: a sidewalk or patio at 4 inches, a driveway at 4 to 6 inches, a footing deeper still. Subgrade rarely sits flat, so probe a few spots with a tape and use the deepest reading rather than the shallowest. If the slab steps down or has a thickened edge, split it into sections, calculate each one, then add the volumes. Forms that bow outward under the weight of wet concrete will quietly eat an extra bag or two, so brace them well.
Bags and coverage by depth
| Mix | Yield per bag | Bags per cubic yard |
|---|---|---|
| 40 lb | 0.30 ft³ | 90 |
| 60 lb | 0.45 ft³ | 60 |
| 80 lb | 0.60 ft³ | 45 |
One cubic yard spread at a given depth covers a set area: 81 square feet at 4 inches, 54 square feet at 6 inches, and 40.5 square feet at 8 inches. Use that as a quick sanity check against the calculator before you place an order.
Tips from the field
Add 5 to 10 percent to your concrete order. Subgrade dips, form deflection and a bit of spillage all draw from the same pile, and running short mid-pour means a cold joint or a frantic trip for more bags. Order the higher end of that range if your base is rough or you are working alone. Cured concrete weighs roughly 140 to 150 pounds per cubic foot, so a single yard lands around two tons. That weight is why an unstable form fails fast, and why footings need a compacted base under them.
Buying context
Ready-mix delivered ran about $125 to $195 per cubic yard through 2025 and 2026 for standard 3,000 to 4,000 PSI mixes, with the NRMCA national average reported near $180 per yard. Short-load and delivery fees can change the picture on small jobs, which is part of why bagged mix often wins under a yard. If you are mixing your own from raw materials, a common ratio is 1 part cement, 2 parts sand and 3 parts gravel by volume, with a water-to-cement ratio around 0.5.
Sources: Quikrete Concrete Mix data sheet, HomeGuide concrete prices.
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