How it's worked out
- Area: 4 × 4 = 16 sq ft
- Volume: 16 sq ft × 4 in ÷ 12 = 5.3 cu ft
- Add 10%: 5.3 × 1.1 = 5.9 cu ft
- Cubic yards: 5.9 ÷ 27 = 0.22 yd³
- 80 lb bags: 5.9 ÷ 0.6 cu ft per bag = 10 bags
4x4 slab at other thicknesses
| Thickness | Cubic yards | 80 lb bags | 60 lb bags |
|---|---|---|---|
| 4 in | 0.22 | 10 | 14 |
| 5 in | 0.27 | 13 | 17 |
| 6 in | 0.33 | 15 | 20 |
4 inches suits patios, sheds and walkways. Driveways and garage floors usually get 5 to 6 inches.
At under a yard, bagged concrete and a rented mixer are usually the easiest option.
Other common sizes
- 4 × 4 ft
- 10 × 10 ft
- 10 × 12 ft
- 10 × 20 ft
- 12 × 12 ft
- 12 × 16 ft
- 12 × 20 ft
- 12 × 24 ft
- 16 × 16 ft
- 20 × 20 ft
- 20 × 24 ft
- 24 × 24 ft
- 30 × 30 ft
- 30 × 40 ft
More detail: How Many Bags of Concrete Do I Need? (Chart + Examples)