How Many Bags of Concrete for a 12x20 Shed Base?
A 12x20 slab at 4" needs 147 bags of 80 lb concrete.
147bags
80 lb bags · estimated $1026.06 at $6.98/bag
Advertisement placeholder (ad-slot-1)
Estimated cost: ~$1026.06 (147 × $6.98/bag, Spring 2026 pricing)
Quick presets
Bag size
Multi-bag comparison
| Bag size | Bags | Price/bag | Total |
|---|---|---|---|
| 80 lbBest value | 147 | $6.98 | $1026.06 |
| 60 lb | 196 | $5.98 | $1172.08 |
| 40 lb | 294 | $4.98 | $1464.12 |
Prices are spring 2026 estimates. Above ~60 bags, price a ready-mix truck too — it is often cheaper.
Material list
- 147 × 80 lb concrete mix bags — $1026.06 @ $6.98/bag (Spring 2026)Home Depot ↗Lowe's ↗
- Wheelbarrow or mixing tub
- Mixing hoe or drill paddle
- Margin trowel or float
Advertisement placeholder (ad-slot-2)
147 bags(80 lb)
$1026.06
How this is calculated
We convert your dimensions to cubic feet, add a 10% waste buffer for spillage and an uneven subgrade, then divide by the bag's yield and round up to the next full bag.
FAQ
How many bags of concrete for a 12x20 shed base?
A 12x20 shed base at 4 inches needs about 147 bags of 80 lb or 196 bags of 60 lb concrete, including a 10% waste allowance.
How much does a 12x20 concrete shed base cost?
About $1026 in 80 lb bags at current prices. Above ~60 bags, a ready-mix truck is often cheaper — the page shows both.
How many cubic feet of concrete is a 12x20 slab at 4 inches?
About 80 cubic feet, or 88 cubic feet once the 10% waste buffer is added.
Related pages
← Back to Shed Base Concrete Calculator
- How Many Bags of Concrete for a 8x12 Shed Base?
- How Many Bags of Concrete for a 10x10 Shed Base?
- How Many Bags of Concrete for a 10x12 Shed Base?
- How Many Bags of Concrete for a 12x12 Shed Base?
- How Many Bags of Concrete for a 10x16 Shed Base?
- How Many Bags of Concrete for a 12x16 Shed Base?
- How Many Bags of Concrete for a 10x20 Shed Base?
- How Many Bags of Concrete for a 12x24 Shed Base?