Pour a Concrete Slab: Calculators in Order

A slab is a short job with one deadline: once the truck arrives or the first bag is wet, you have a few hours to place, level and finish. Every number below is worked out before that day, so the order matters more than speed.

Start with the volume. A 10 x 10 ft slab that is 4 in thick holds 33.3 cu ft, or 1.23 cu yd. Add 5 to 10 percent for uneven ground and spillage and you order about 1.4 cu yd. That is more than a homeowner mixes by hand comfortably: an 80 lb bag yields about 0.6 cu ft, so the same slab is 56 bags before waste. Somewhere above roughly 1 cu yd, ready-mix starts to make sense, but small-load fees vary, so ask the plant for the minimum.

Thickness follows the use. Four inches suits a patio or a shed floor; a driveway or garage floor is usually thicker and reinforced. The base under the slab matters as much as the slab: 4 in of compacted crushed stone drains water and keeps the slab from settling unevenly. Stone is sold by the ton or the yard, so convert once and ask the supplier for the yield of the stone you pick.

Reinforcement holds cracks tight rather than preventing them; control joints decide where cracks form, and a common rule is a joint spacing in feet of two to three times the slab thickness in inches. Finish the plan with a cost range, and save each list to your project list so the truck, the rebar and the stone end up on one printout.