How to use
- 1
Choose slab, column or steps.
- 2
Enter the size in feet and inches and how many.
- 3
Read cubic yards, cubic feet and bag counts, with extra for waste.
When to use it
Fence posts
Enter the hole diameter, depth and post count to get the number of bags.
Patio or shed slab
Get cubic yards to order ready-mix, or bags if you mix it yourself.
Concrete steps
Enter rise, run and width to estimate a small stair.
Good to know
- An 80 lb bag makes about 0.6 cu ft; a 60 lb bag 0.45; a 40 lb bag 0.3.
- Order ready-mix by the cubic yard when you need more than about 1 yard.
- Add 5–10% for spills and uneven ground.
FAQ
How many bags for a 10×10 slab 4 inches thick?
About 33.3 cu ft, so 56 bags of 80 lb (before waste).
How many cubic feet in a yard?
27.
Does it include gravel base?
No, only the concrete.