Concrete for a 24x36 Slab
Order 11.73 yd with 10% waste — or 480 × 80 lb bags / 640 × 60 lb bags.
By thickness
| Thickness | Cubic yards | +10% waste | 80 lb bags | Typical use |
|---|---|---|---|---|
| 4" | 10.67 | 11.73 | 480 | Patio, shed pad, walkway |
| 5" | 13.33 | 14.67 | 600 | Light vehicle traffic |
| 6" | 16.00 | 17.60 | 720 | Driveway, garage |
Bags or the truck?
For this 864 sq ft slab at 4": bags ≈ $3,120 (480 × 80 lb — that's 38,400 lb of mixing) vs ready-mix ≈ $1,653 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 24x36 slab?
A 24x36 slab at the standard 4-inch thickness needs 10.67 cubic yards of concrete — order 11.73 yards with a 10% waste margin. At 6 inches it needs 16.00 yards.
How many bags of concrete for a 24x36 slab?
At 4 inches thick: 480 bags of 80 lb concrete mix or 640 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 24x36 slab?
Ready-mix. Bags for this slab would cost about $3,120 in material and require mixing 38,400 lb by hand; a delivered order runs roughly $1,653 and arrives ready to pour.