20x30 Concrete Slab: Bags, Yards & Cost
A 20 × 30 ft slab (600 sq ft) 4 in thick is 200.0 cu ft, or 7.41 cu yd: 334 bags of 80 lb Quikrete Concrete Mix (350 with a 5% margin), 445 bags of 60 lb, or 218 bags of 80 lb Sakrete Maximizer. The 80 lb bags weigh 26,720 lb in total.
Your cost and bags vs a truck
Set up for: a 20 × 30 ft slab · Different project?
20x30 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 | 7.41 | 7.78 | 334 | 445 | 218 | 334 |
| 5 in | 9.26 | 9.72 | 417 | 556 | 272 | 417 |
| 6 in | 11.1 | 11.7 | 500 | 667 | 327 | 500 |
Other sizes: 10x10 · 12x12 · 20x20 · 8x8 · 10x12 · 30x30 · 8x10 · 12x24 · 12x36 · 20x40
FAQ
How many bags of concrete for a 20x30 slab?
At 4 in thick: 334 bags of 80 lb Quikrete Concrete Mix or 445 of 60 lb (whole bags, no margin). At 6 in: 500 of 80 lb.
How many yards of concrete for a 20x30 slab?
7.41 cu yd at 4 in, 9.26 at 5 in and 11.1 at 6 in, before the 4–10% NRMCA suggests adding when you order.
How much does a 20x30 concrete slab cost?
We don't publish prices because they change by store and region. Multiply 334 bags by your store's 80 lb bag price, or 7.78 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