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How Many Bags of Concrete Do You Need?

How many 80, 60 and 40 lb bags make a cubic yard, with a chart for common 4-inch slabs and the published yields behind the numbers.

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Reading time2 min
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Key takeaways

  • One cubic yard takes 45 bags of 80 lb, 60 of 60 lb, or 90 of 40 lb, using QUIKRETE's yields.
  • An 80 lb bag yields about 0.60 cubic feet.
  • Yields are approximate and vary by product, so check the bag.

Using QUIKRETE's published yields, one cubic yard takes about 45 bags of 80 lb, 60 bags of 60 lb, or 90 bags of 40 lb. A cubic yard is 27 cubic feet, and each figure is 27 divided by that bag's yield.

Bags per cubic yard

Bag size Yield per bag Bags per cubic yard Bag weight per yard
80 lb 0.60 cu ft 45 3,600 lb
60 lb 0.45 cu ft 60 3,600 lb
40 lb 0.30 cu ft 90 3,600 lb

QUIKRETE also lists 50 lb bags, at 0.375 cubic feet, and 90 lb bags, at 0.675 cubic feet, where available.

Bags for common 4-inch slabs

These are rounded up, with no extra allowance.

Slab size Volume 80 lb bags 60 lb bags 40 lb bags
4 × 4 ft 5.3 cu ft 9 12 18
8 × 8 ft 21.3 cu ft 36 48 72
10 × 10 ft 33.3 cu ft 56 75 112
10 × 20 ft 66.7 cu ft 112 149 223

For any other size or thickness, use the concrete slab calculator.

How to work it out yourself

  1. Multiply length × width × thickness, all in feet. Four inches is 4 ÷ 12, or 0.33 feet.
  2. Add an allowance for waste.
  3. Divide by the bag's yield, then round up.

Which bag size should you choose?

The total weight per yard is the same, so it's mostly about handling and price. Smaller bags are easier to lift, but you'll have more to open and mix. Compare price per cubic foot at your store: divide the bag price by its yield.

How many batches is that?

QUIKRETE says to allow at least 1 cubic foot of mixer capacity for each 80 lb bag mixed at one time. So a 3-cubic-foot mixer takes about 3 bags a batch:

80 lb bags Batches in a 3 cu ft mixer Water, at 6 to 9 pints per bag
9 3 7 to 10 gallons
36 12 27 to 41 gallons
56 19 42 to 63 gallons
112 38 84 to 126 gallons

Thinking in batches shows the real work of a pour. Plan how you'll keep the concrete moving, and see water per bag for mixing details.

Frequently asked questions

How many 80 lb bags of concrete are in a yard?

About 45, based on a yield of 0.60 cubic feet per bag.

How much does an 80 lb bag of concrete cover?

It yields about 0.60 cubic feet. At 4 inches thick, that covers about 1.8 square feet.

Are the yields the same for every brand?

Not necessarily. These are QUIKRETE's Concrete Mix figures, so check the bag if you buy another brand or product.

Sources

We use primary sources where we can: building codes, federal rules and manufacturer documents. Read our editorial standards.