Planning result
An 8x10 shed slab at 4 inches thick uses about 0.99 cubic yards before waste and about 1.09 cubic yards with 10% waste. Bagged concrete is roughly 49 80 lb bags after waste.
Assumptions
| Slab size | 8 ft by 10 ft. |
|---|---|
| Thickness | 4 inches, converted to 0.333 ft. |
| Waste | 10% for base and form variation. |
| Bag yield | 0.6 cubic ft per 80 lb bag for planning. |
Calculation
| Step | Result | Formula |
|---|---|---|
| Area | 80 sq ft | 8 x 10 |
| Volume | 26.7 cubic ft | 80 x 0.333 |
| Cubic yards | 0.99 yd3 | 26.7 / 27 |
| With waste | 1.09 yd3 | 0.99 x 1.10 |
| 80 lb bags before waste | 45 bags | 26.7 / 0.6, rounded up |
| 80 lb bags with waste | 49 bags | 45 x 1.10, rounded up |
Shed loads still matter
A calculator estimates material volume, not structural adequacy. Shed size, soil, drainage, frost, and local code can change slab design.
Keep base material separate
Compacted gravel, vapor barrier, forms, reinforcement, anchors, and finishing tools are separate from concrete volume.
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 much concrete for an 8x10 shed slab?
About 1.09 cubic yards with 10% waste at 4 inches thick.
How many 80 lb bags for an 8x10 slab?
This example lands near 49 bags after waste.
Is 4 inches enough for a shed slab?
It depends on shed load, soil, base, frost, and local requirements.