30x30 Concrete Slab: Bags, Yards & Cost
A 30 × 30 ft slab (900 sq ft) 4 in thick is 300.0 cu ft, or 11.1 cu yd: 500 bags of 80 lb Quikrete Concrete Mix (525 with a 5% margin), 667 bags of 60 lb, or 327 bags of 80 lb Sakrete Maximizer. The 80 lb bags weigh 40,000 lb in total.
Your cost and bags vs a truck
Set up for: a 30 × 30 ft slab · Different project?
30x30 slab at 4, 5 and 6 inches
| Thickness | Cu yd | With 5% | 80 lb Quikrete | 60 lb Quikrete | 80 lb Maximizer | 80 lb 5000 Plus |
|---|---|---|---|---|---|---|
| 4 in | 11.1 | 11.7 | 500 | 667 | 327 | 500 |
| 5 in | 13.9 | 14.6 | 625 | 834 | 408 | 625 |
| 6 in | 16.7 | 17.5 | 750 | 1,000 | 490 | 750 |
Other sizes: 10x10 · 12x12 · 20x20 · 8x8 · 10x12 · 8x10 · 12x24 · 12x36 · 20x30 · 20x40
FAQ
How many bags of concrete for a 30x30 slab?
At 4 in thick: 500 bags of 80 lb Quikrete Concrete Mix or 667 of 60 lb (whole bags, no margin). At 6 in: 750 of 80 lb.
How many yards of concrete for a 30x30 slab?
11.1 cu yd at 4 in, 13.9 at 5 in and 16.7 at 6 in, before the 4–10% NRMCA suggests adding when you order.
How much does a 30x30 concrete slab cost?
We don't publish prices because they change by store and region. Multiply 500 bags by your store's 80 lb bag price, or 11.7 cu yd (4 in, with 5%) by your plant's price per yard plus delivery and short-load fees. Type those into the calculator to compare.
Sources
- Quikrete: QUIKRETE Concrete Mix (No. 1101) data sheet · fetched and reviewed 2026-11-10
- Quikrete: QUIKRETE online project calculator (calculator.js) · fetched and reviewed 2026-11-10
- Sakrete: Sakrete Maximizer Concrete Mix technical data sheet · fetched and reviewed 2026-11-10
- Sakrete: Sakrete 5000 Plus Concrete Mix technical data sheet · fetched and reviewed 2026-11-10
- NRMCA: CIP 31: Ordering Ready Mixed Concrete · fetched and reviewed 2026-11-10