12x36 Concrete Slab: Bags, Yards & Cost
A 12 × 36 ft slab (432 sq ft) 4 in thick is 144.0 cu ft, or 5.33 cu yd: 240 bags of 80 lb Quikrete Concrete Mix (252 with a 5% margin), 320 bags of 60 lb, or 157 bags of 80 lb Sakrete Maximizer. The 80 lb bags weigh 19,200 lb in total.
Your cost and bags vs a truck
Set up for: a 12 × 36 ft slab · Different project?
12x36 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 | 5.33 | 5.60 | 240 | 320 | 157 | 240 |
| 5 in | 6.67 | 7.00 | 300 | 400 | 196 | 300 |
| 6 in | 8.00 | 8.40 | 360 | 480 | 235 | 360 |
Other sizes: 10x10 · 12x12 · 20x20 · 8x8 · 10x12 · 30x30 · 8x10 · 12x24 · 20x30 · 20x40
FAQ
How many bags of concrete for a 12x36 slab?
At 4 in thick: 240 bags of 80 lb Quikrete Concrete Mix or 320 of 60 lb (whole bags, no margin). At 6 in: 360 of 80 lb.
How many yards of concrete for a 12x36 slab?
5.33 cu yd at 4 in, 6.67 at 5 in and 8.00 at 6 in, before the 4–10% NRMCA suggests adding when you order.
How much does a 12x36 concrete slab cost?
We don't publish prices because they change by store and region. Multiply 240 bags by your store's 80 lb bag price, or 5.60 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