Concrete for a 12x24 Slab
Order 3.91 yd with 10% waste — or 160 × 80 lb bags / 214 × 60 lb bags.
By thickness
| Thickness | Cubic yards | +10% waste | 80 lb bags | Typical use |
|---|---|---|---|---|
| 4" | 3.56 | 3.91 | 160 | Patio, shed pad, walkway |
| 5" | 4.44 | 4.89 | 200 | Light vehicle traffic |
| 6" | 5.33 | 5.87 | 240 | Driveway, garage |
Bags or the truck?
For this 288 sq ft slab at 4": bags ≈ $1,040 (160 × 80 lb — that's 12,800 lb of mixing) vs ready-mix ≈ $626 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 12x24 slab?
A 12x24 slab at the standard 4-inch thickness needs 3.56 cubic yards of concrete — order 3.91 yards with a 10% waste margin. At 6 inches it needs 5.33 yards.
How many bags of concrete for a 12x24 slab?
At 4 inches thick: 160 bags of 80 lb concrete mix or 214 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 12x24 slab?
Ready-mix. Bags for this slab would cost about $1,040 in material and require mixing 12,800 lb by hand; a delivered order runs roughly $626 and arrives ready to pour.