Concrete footings and slabs
Enter the footings or the slab. This works out the cubic yards and the bags that pour it.
Pour
in
in
Bag size
Buy
8bags, 80 lb
Cubic feet
4.71
Cubic yards
0.175
By bag size
- 40 lb bags0.30 ft³ per bag
- 16
- 60 lb bags0.45 ft³ per bag
- 11
- 80 lb bags0.60 ft³ per bag
- 8
Where to buy this
- 8 × 80 lb bagsHome DepotLowe's
Buy one more bag than the table says — concrete you did not need is cheaper than a second trip mid-pour.
Plain search links, nothing sponsored. Prices and stock are the shop's, and a local lumberyard will usually beat both on solid stock.
For anything past a couple of yards, ready-mix delivered by truck is usually both cheaper and far less labour than mixing that many bags by hand.
About mixing concrete
- How many bags make a cubic yard?
- 45 bags of 80 lb, 60 bags of 60 lb, or 90 bags of 40 lb — these are the yields Quikrete and Sakrete print on the bag itself, not an estimate, which is why they come out to round numbers. Smaller bags cost more per cubic foot, so the tradeoff is money against how much you want to lift.
- Why is a footing's volume based on its diameter, not its width?
- Because a post footing is normally dug or formed round, with a post-hole digger or a cardboard tube form, so the volume is a cylinder — π times the radius squared times the depth — rather than the length-times-width-times-height of a slab.
- Should I round up?
- Yes, by at least one extra bag per footing and a few percent on a slab. Bags settle air out unevenly, a form is rarely perfectly straight-sided, and running short partway through a pour with the mix already wet is a much worse afternoon than one leftover bag.
- When should I order ready-mix instead of mixing bags?
- Past about a cubic yard, most people are better off with a delivered truck or a trailer-mounted mixer. A yard of concrete is 45 bags of 80 lb — over 3,600 lb to move, mix and place by hand — and ready-mix cures more consistently because the whole pour goes in at once rather than bag by bag.