How Many Bags of Concrete for a 8x8 Slab?
A 8x8 slab at 4" needs 40 bags of 80 lb concrete.
40bags
80 lb bags · estimated $279.20 at $6.98/bag
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Estimated cost: ~$279.20 (40 × $6.98/bag, Spring 2026 pricing)
Quick presets
Bag size
Material list
- 40 × 80 lb concrete mix bags — $279.20 @ $6.98/bag (Spring 2026)Home Depot ↗Lowe's ↗
- Wheelbarrow or mixing tub
- Mixing hoe or drill paddle
- Margin trowel or float
Multi-bag comparison
| Bag size | Bags | Price/bag | Total |
|---|---|---|---|
| 80 lbBest value | 40 | $6.98 | $279.20 |
| 60 lb | 53 | $5.98 | $316.94 |
| 40 lb | 79 | $4.98 | $393.42 |
Prices are spring 2026 estimates. Above ~60 bags, price a ready-mix truck too — it is often cheaper.
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40 bags(80 lb)
$279.20
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 8x8 slab?
A 8x8 slab at 4 inches needs about 40 bags of 80 lb or 53 bags of 60 lb concrete, including a 10% waste allowance.
How much does a 8x8 concrete slab cost?
About $279 in 80 lb bags at current prices.
How many cubic feet of concrete is a 8x8 slab at 4 inches?
About 21.3 cubic feet, or 23.5 cubic feet once the 10% waste buffer is added.
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