Quick answer
A cubic yard of concrete takes 45 bags of 80 lb mix, 60 bags of 60 lb mix or 90 bags of 40 lb mix, based on QUIKRETE's yields of 0.6, 0.45 and 0.3 cubic feet per bag. With 10% extra for spills and an uneven base, that's 50 bags of 80 lb mix.
Bags per cubic yard
Each bag size makes about the same amount of concrete every time. QUIKRETE's data sheet lists these yields:
| Bag size | Yield per bag | Bags per cubic yard | With 10% extra |
|---|---|---|---|
| 80 lb bag | 0.6 cu ft | 45 | 50 |
| 60 lb bag | 0.45 cu ft | 60 | 66 |
| 40 lb bag | 0.3 cu ft | 90 | 99 |
A yard of bagged concrete is about 3,600 lb of dry mix whichever size you buy: 45 × 80 lb, 60 × 60 lb or 90 × 40 lb. Smaller bags are easier to lift but mean more bags to open and mix.
Bags for common slabs
At 4 inches thick, the usual depth for a patio, walkway or shed pad, one cubic yard covers 81 sq ft. Volumes and bag counts below include 10% extra, and bags are rounded up to whole bags:
| Slab, 4 in thick | Concrete, incl. 10% | 80 lb bags | 60 lb bags |
|---|---|---|---|
| 4 × 4 ft | 0.22 cu yd | 10 | 14 |
| 10 × 10 ft | 1.36 cu yd | 62 | 82 |
| 12 × 12 ft | 1.96 cu yd | 88 | 118 |
| 10 × 20 ft | 2.72 cu yd | 123 | 163 |
| 20 × 20 ft | 5.43 cu yd | 245 | 326 |
At 6 inches thick a slab needs half as much again: a 10 × 10 ft slab takes 92 bags of 80 lb mix instead of 62.
These yields are for QUIKRETE Concrete Mix. Other products, such as high-strength or fast-setting mixes and other brands, can yield different amounts, so use the figure printed on the bag you buy. For a yard or more, the slab calculator also compares the cost of a ready-mix delivery with your own prices. For footings or anything structural, check your local building code first.
The concrete slab calculator gives the bags for any size and thickness, and the post hole concrete calculator does the same for fence and deck posts.
How to work it out yourself
- Multiply length × width in feet × thickness in inches, then divide by 12. That gives cubic feet.
- Add 10% for spills and an uneven base.
- Divide by the yield on the bag: 0.6 for 80 lb, 0.45 for 60 lb or 0.3 for 40 lb. Round up.
For a 10 × 10 ft slab 4 inches thick: 10 × 10 × 4 ÷ 12 = 33.3 cu ft, plus 10% is 36.7 cu ft, and ÷ 0.6 rounds up to 62 bags of 80 lb mix.
Water per bag
QUIKRETE's data sheet starts an 80 lb bag of its Concrete Mix at about 6 pints of water and puts the final amount at about 6 to 9 pints. For a 60 lb bag it's about 4 to 7 pints, and for a 40 lb bag about 3 to 4½ pints. Add the extra a little at a time, only until the mix is stiff and moldable with no standing puddles.
Frequently asked questions
How many 80 lb bags of concrete make a yard?
45, since each 80 lb bag yields about 0.6 cu ft and a cubic yard is 27 cu ft. Buy about 50 to allow 10% extra.
How many 60 lb bags of concrete make a yard?
60 bags, at about 0.45 cu ft each.
How many bags of concrete do I need for a 10 x 10 slab?
About 62 bags of 80 lb mix for a 10 × 10 ft slab 4 inches thick, including 10% extra. The slab itself is 1.23 cubic yards, or 1.36 with the extra.
How much does a yard of bagged concrete weigh?
About 3,600 lb of dry mix: 45 bags at 80 lb each.
Calculators for this
Concrete Slab
Enter slab size and thickness to get cubic yards, exact 40, 60 or 80 lb bag counts and ready-mix cost, with waste included.
Post Hole & Footing Concrete
How many bags of concrete per post?
Concrete Steps
Enter the number of steps, rise, tread depth, width and landing to get cubic yards and bags of concrete, with code checks.
Published 2026-11-03. Sources: QUIKRETE Concrete Mix No. 1101, data sheet (yield and water per bag). See how we calculate.