Concrete for a 10x20 Slab
Order 2.72 yd with 10% waste — or 112 × 80 lb bags / 149 × 60 lb bags.
By thickness
| Thickness | Cubic yards | +10% waste | 80 lb bags | Typical use |
|---|---|---|---|---|
| 4" | 2.47 | 2.72 | 112 | Patio, shed pad, walkway |
| 5" | 3.09 | 3.40 | 139 | Light vehicle traffic |
| 6" | 3.70 | 4.07 | 167 | Driveway, garage |
Bags or the truck?
For this 200 sq ft slab at 4": bags ≈ $728 (112 × 80 lb — that's 8,960 lb of mixing) vs ready-mix ≈ $458 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 10x20 slab?
A 10x20 slab at the standard 4-inch thickness needs 2.47 cubic yards of concrete — order 2.72 yards with a 10% waste margin. At 6 inches it needs 3.70 yards.
How many bags of concrete for a 10x20 slab?
At 4 inches thick: 112 bags of 80 lb concrete mix or 149 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 10x20 slab?
Ready-mix. Bags for this slab would cost about $728 in material and require mixing 8,960 lb by hand; a delivered order runs roughly $458 and arrives ready to pour.