How the Quikrete bags calculator works
Once you know the volume of concrete needed, the next question is how many bags to buy. This Quikrete bag calculator converts your slab or form dimensions into cubic feet and divides that volume by the yield of one bag.
Bag quantity formula
volume = length × width × depth in feet
bags = volume with waste ÷ yield per bag
Why the yield matters
Concrete mix products do not all produce the same volume. Bag weight alone is not enough to know the yield, because the product formulation can differ. That is why the calculator lets you use the yield printed on your exact product packaging.
Example
A 10 ft × 10 ft slab at 4 inches deep is about 3.70 cubic yards, or 100 cubic feet.
At a 0.60 cu ft yield per 80 lb bag, 10% extra gives an estimate of about 184 bags.
The example is intentionally based on the entered yield, so replace it with the yield of the product you are actually buying.
Frequently asked questions
How many bags of Quikrete do I need?
Enter the dimensions of the area, choose your bag size, and make sure the yield matches the exact product. The calculator then rounds up to whole bags.
Is this a how many bags of Quikrete calculator, or does it work for other brands too?
It is built around Quikrete's published yields, since that is what most people search for by name. The same volume math applies to other premixed bagged concrete, but you would need to swap in that product's yield per bag.
Is the yield the same for every Quikrete bag?
No. Different products and bag sizes can have different yields. Check the packaging for the product you plan to use.
Should I add extra bags?
A small allowance can help with uneven forms and placement loss. The calculator includes a waste percentage so you can make that adjustment.
Can I use this for post holes?
Yes, if you can estimate the total volume of the holes. For several holes, calculate one hole and multiply by the number of holes.