Concrete for a 6x6 Slab
Order 0.49 yd with 10% waste — or 20 × 80 lb bags / 27 × 60 lb bags.
By thickness
| Thickness | Cubic yards | +10% waste | 80 lb bags | Typical use |
|---|---|---|---|---|
| 4" | 0.44 | 0.49 | 20 | Patio, shed pad, walkway |
| 5" | 0.56 | 0.61 | 25 | Light vehicle traffic |
| 6" | 0.67 | 0.73 | 30 | Driveway, garage |
Bags or the truck?
For this 36 sq ft slab at 4": bags ≈ $130 (20 × 80 lb — that's 1,600 lb of mixing) vs ready-mix ≈ $144 delivered. Bags are competitive at this size. Prices are national ballparks — your local quote rules.
Adjust the numbers
Common questions
How much concrete do I need for a 6x6 slab?
A 6x6 slab at the standard 4-inch thickness needs 0.44 cubic yards of concrete — order 0.49 yards with a 10% waste margin. At 6 inches it needs 0.67 yards.
How many bags of concrete for a 6x6 slab?
At 4 inches thick: 20 bags of 80 lb concrete mix or 27 bags of 60 lb. At this size, bags are a reasonable DIY option.
Should I use bags or ready-mix for a 6x6 slab?
Either works at this size. Bags cost about $130; ready-mix about $144 after the short-load fee. Bags save money if your time is free; the truck saves your weekend.