How much concrete is a 12×12 slab?
A 12-by-12-foot slab covers 144 square feet. At the standard 4-inch thickness that's about 1.78 cubic yards of concrete before waste, or roughly 1.96 yards once you add a 10% allowance. At about 1.96 cubic yards a single ready-mix truck (roughly 10 cubic yards) delivers this in one load with room to spare. The calculator above is pre-filled to these dimensions; change the thickness or price to match your job.
Concrete for a 12×12 slab by thickness
| Thickness | Concrete to order | 80 lb bags | Material cost |
|---|---|---|---|
| 4″ (standard) | 1.96 yd³ | 89 | $313 |
| 5″ | 2.44 yd³ | 110 | $391 |
| 6″ | 2.93 yd³ | 132 | $469 |
Material cost at $160/yd³ ready-mix, before delivery fees. Cost data updated June 2026.
Common questions
How many yards of concrete for a 12x12 slab?
A 12x12 slab at 4 inches thick needs about 1.78 cubic yards before waste. Add 5-10% extra so you don't come up short. Change the thickness in the calculator above to see how it affects the total.
How many bags of concrete for a 12x12 slab?
At 4 inches thick that's roughly 89 eighty-pound bags with a 10% allowance. Past about 1 cubic yard (around 45 bags), ready-mix delivery is usually cheaper and far less work than mixing bags by hand.
What does a 12x12 slab cost?
Material alone is a small share of the total. Installed, slabs this size run a wide range depending on thickness, finish, site prep, and region. Use the calculator's installed-cost range as a ballpark, then compare local quotes for a real price.