Concrete for a 6x8 Slab
Order 0.65 yd with 10% waste — or 27 × 80 lb bags / 36 × 60 lb bags.
By thickness
| Thickness | Cubic yards | +10% waste | 80 lb bags | Typical use |
|---|---|---|---|---|
| 4" | 0.59 | 0.65 | 27 | Patio, shed pad, walkway |
| 5" | 0.74 | 0.81 | 34 | Light vehicle traffic |
| 6" | 0.89 | 0.98 | 40 | Driveway, garage |
Bags or the truck?
For this 48 sq ft slab at 4": bags ≈ $176 (27 × 80 lb — that's 2,160 lb of mixing) vs ready-mix ≈ $167 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 6x8 slab?
A 6x8 slab at the standard 4-inch thickness needs 0.59 cubic yards of concrete — order 0.65 yards with a 10% waste margin. At 6 inches it needs 0.89 yards.
How many bags of concrete for a 6x8 slab?
At 4 inches thick: 27 bags of 80 lb concrete mix or 36 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 6x8 slab?
Ready-mix. Bags for this slab would cost about $176 in material and require mixing 2,160 lb by hand; a delivered order runs roughly $167 and arrives ready to pour.