Concrete for a 4x4 Slab
A 4x4 slab at 4" thick needs
0.20 cu yd
Order 0.22 yd with 10% waste — or 9 × 80 lb bags / 12 × 60 lb bags.
By thickness
| Thickness | Cubic yards | +10% waste | 80 lb bags | Typical use |
|---|---|---|---|---|
| 4" | 0.20 | 0.22 | 9 | Patio, shed pad, walkway |
| 5" | 0.25 | 0.27 | 12 | Light vehicle traffic |
| 6" | 0.30 | 0.33 | 14 | Driveway, garage |
Bags or the truck?
For this 16 sq ft slab at 4": bags ≈ $59 (9 × 80 lb — that's 720 lb of mixing) vs ready-mix ≈ $106 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 4x4 slab?
A 4x4 slab at the standard 4-inch thickness needs 0.20 cubic yards of concrete — order 0.22 yards with a 10% waste margin. At 6 inches it needs 0.30 yards.
How many bags of concrete for a 4x4 slab?
At 4 inches thick: 9 bags of 80 lb concrete mix or 12 bags of 60 lb. At this size, bags are a reasonable DIY option.
Should I use bags or ready-mix for a 4x4 slab?
Either works at this size. Bags cost about $59; ready-mix about $106 after the short-load fee. Bags save money if your time is free; the truck saves your weekend.