Concrete
Slabs, footings and post holes, in yards and in bags.
3 calculators
- Concrete Slab CalculatorFor a patio, a shed base or a garage floor. Enter the size and thickness and this gives you the yards to order, or the bags to mix if the pour is small.
- Concrete Footing CalculatorFor a strip footing under a wall, a garage or a deck. Enter the trench width, the thickness and how far it runs in total.
- Post Hole Concrete CalculatorThe post takes up part of the hole, so the concrete you need is the hole minus the post. This does that subtraction for you and converts the result into bags.
Slab, footing or post hole
Use the slab calculator for anything flat and rectangular: a patio, a shed base or a garage floor. Use the footing calculator for the long strip of concrete that sits under a wall, and the post hole calculator when you are setting fence or deck posts, where the post itself takes up some of the hole.
Every result is given in cubic yards, for ordering ready-mix, and in 40, 60 and 80 pound bags, for mixing it yourself. As a rough guide, bags make sense up to about one cubic yard. Beyond that, a truck is usually cheaper and the concrete is more even.
Concrete is unforgiving if you run short, because a second batch poured later leaves a weak joint. Add 5 to 10 percent to the result for spillage and for ground that is not perfectly level.