How Many Bags of Concrete for a 20x24 Slab?
A 20x24 slab at 4" needs 294 bags of 80 lb concrete.
294bags
80 lb bags · estimated $2052.12 at $6.98/bag
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Estimated cost: ~$2052.12 (294 × $6.98/bag, Spring 2026 pricing)
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Bag size
Multi-bag comparison
| Bag size | Bags | Price/bag | Total |
|---|---|---|---|
| 80 lbBest value | 294 | $6.98 | $2052.12 |
| 60 lb | 392 | $5.98 | $2344.16 |
| 40 lb | 587 | $4.98 | $2923.26 |
Prices are spring 2026 estimates. Above ~60 bags, price a ready-mix truck too — it is often cheaper.
Material list
- 294 × 80 lb concrete mix bags — $2052.12 @ $6.98/bag (Spring 2026)Home Depot ↗Lowe's ↗
- Wheelbarrow or mixing tub
- Mixing hoe or drill paddle
- Margin trowel or float
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294 bags(80 lb)
$2052.12
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 20x24 slab?
A 20x24 slab at 4 inches needs about 294 bags of 80 lb or 392 bags of 60 lb concrete, including a 10% waste allowance.
How much does a 20x24 concrete slab cost?
About $2052 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 20x24 slab at 4 inches?
About 160 cubic feet, or 176 cubic feet once the 10% waste buffer is added.
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