Concrete for a 5x5 Slab
A 5x5 slab at 4" thick needs
0.31 cu yd
Order 0.34 yd with 10% waste — or 14 × 80 lb bags / 19 × 60 lb bags.
By thickness
| Thickness | Cubic yards | +10% waste | 80 lb bags | Typical use |
|---|---|---|---|---|
| 4" | 0.31 | 0.34 | 14 | Patio, shed pad, walkway |
| 5" | 0.39 | 0.42 | 18 | Light vehicle traffic |
| 6" | 0.46 | 0.51 | 21 | Driveway, garage |
Bags or the truck?
For this 25 sq ft slab at 4": bags ≈ $91 (14 × 80 lb — that's 1,120 lb of mixing) vs ready-mix ≈ $123 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 5x5 slab?
A 5x5 slab at the standard 4-inch thickness needs 0.31 cubic yards of concrete — order 0.34 yards with a 10% waste margin. At 6 inches it needs 0.46 yards.
How many bags of concrete for a 5x5 slab?
At 4 inches thick: 14 bags of 80 lb concrete mix or 19 bags of 60 lb. At this size, bags are a reasonable DIY option.
Should I use bags or ready-mix for a 5x5 slab?
Either works at this size. Bags cost about $91; ready-mix about $123 after the short-load fee. Bags save money if your time is free; the truck saves your weekend.