Concrete for a 12x12 Slab
Order 1.96 yd with 10% waste — or 80 × 80 lb bags / 107 × 60 lb bags.
By thickness
| Thickness | Cubic yards | +10% waste | 80 lb bags | Typical use |
|---|---|---|---|---|
| 4" | 1.78 | 1.96 | 80 | Patio, shed pad, walkway |
| 5" | 2.22 | 2.44 | 100 | Light vehicle traffic |
| 6" | 2.67 | 2.93 | 120 | Driveway, garage |
Bags or the truck?
For this 144 sq ft slab at 4": bags ≈ $520 (80 × 80 lb — that's 6,400 lb of mixing) vs ready-mix ≈ $351 delivered. The truck wins here. Prices are national ballparks — your local quote rules.
Adjust the numbers
Common questions
How much concrete do I need for a 12x12 slab?
A 12x12 slab at the standard 4-inch thickness needs 1.78 cubic yards of concrete — order 1.96 yards with a 10% waste margin. At 6 inches it needs 2.67 yards.
How many bags of concrete for a 12x12 slab?
At 4 inches thick: 80 bags of 80 lb concrete mix or 107 bags of 60 lb. At this volume, delivered ready-mix is usually cheaper and far less work than mixing bags.
Should I use bags or ready-mix for a 12x12 slab?
Ready-mix. Bags for this slab would cost about $520 in material and require mixing 6,400 lb by hand; a delivered order runs roughly $351 and arrives ready to pour.