Planning result
A 12x16 slab at 4 inches thick uses about 2.37 cubic yards before waste and about 2.61 cubic yards with 10% waste. Bagged concrete would be roughly 118 80 lb bags after waste.
Assumptions
| Slab size | 12 ft by 16 ft. |
|---|---|
| Thickness | 4 inches, converted to 0.333 ft. |
| Waste | 10% for uneven grade and placement. |
| Bag yield | 0.6 cubic ft per 80 lb bag for planning. |
Calculation
| Step | Result | Formula |
|---|---|---|
| Area | 192 sq ft | 12 x 16 |
| Volume | 64.0 cubic ft | 192 x 0.333 |
| Cubic yards | 2.37 yd3 | 64 / 27 |
| With waste | 2.61 yd3 | 2.37 x 1.10 |
| 80 lb bags before waste | 107 bags | 64 / 0.6, rounded up |
| 80 lb bags with waste | 118 bags | 107 x 1.10, rounded up |
This is a ready-mix sized project
The bag count is large enough that ready-mix should be considered early. Hand mixing can create timing and consistency problems on a slab this size.
Confirm depth across the form
A small depth change across 192 sq ft can add meaningful concrete volume. Check forms and base before ordering.
Next step
Use the linked calculator or planning hub to adjust dimensions, waste, coverage, depth, spacing, or product packaging for the real project.
Related guides
FAQ
How many yards for a 12x16 four-inch slab?
About 2.37 cubic yards before waste and about 2.61 cubic yards with 10% waste.
Should I order 2.5 or 3 yards?
The math is near 2.6 yards with waste, but order rules and site conditions should be checked with the supplier.
Does this include a thickened edge?
No. Add thickened edges or footings separately.