Concrete bag calculator
You need
– cubic yards
– cu ft · – m³ · sq ft
- Ready-mix concrete ($160–$195/yd)
- –
- Installed by a contractor
- –
Short answer
Divide your volume in cubic feet by the bag's yield: 0.60 cu ft for an 80 lb bag, 0.45 for 60 lb, 0.30 for 40 lb. One cubic yard takes about 45 bags of 80 lb mix or 60 bags of 60 lb mix. A 10 × 10 ft slab at 4 inches needs 56 bags of 80 lb mix.
| 40 lb bag | 0.3 cu ft · 90 bags per cubic yard[1] |
|---|---|
| 50 lb bag | 0.375 cu ft · 72 bags per cubic yard[1] |
| 60 lb bag | 0.45 cu ft · 60 bags per cubic yard[1] |
| 80 lb bag | 0.6 cu ft · 45 bags per cubic yard[1] |
| 90 lb bag | 0.675 cu ft · 40 bags per cubic yard[1] |
| Bag size | Yield | Bags per cu yd | Bags for 10 × 10 × 4 in |
|---|---|---|---|
| 40 lb | 0.3 cu ft | 90 | 112 |
| 50 lb | 0.375 cu ft | 72 | 89 |
| 60 lb | 0.45 cu ft | 60 | 75 |
| 80 lb | 0.6 cu ft | 45 | 56 |
| 90 lb | 0.675 cu ft | 40 | 50 |
Bags or ready-mix?
Bagged concrete is practical up to about one cubic yard (45 bags of 80 lb mix). Beyond that, a ready-mix truck saves hours of mixing and gives a consistent pour. Use the yardage calculator to size a ready-mix order.
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Frequently asked questions
How many bags of concrete make a yard?
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A cubic yard is 27 cubic feet: about 45 bags of 80 lb mix (0.60 cu ft each), 60 bags of 60 lb mix (0.45 cu ft) or 90 bags of 40 lb mix (0.30 cu ft), based on QUIKRETE's published yields.
How many 80 lb bags of concrete for a 10×10 slab?
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At 4 inches thick, 56 bags with no waste, or 62 with 10% extra.
How many bags of concrete per fence post?
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For a 4×4 post on a 6 ft fence, with the hole sized by QUIKRETE's rule (3× post width, a third of the post's length plus 6 in of gravel), about 4 bags of 50 lb mix or 3 bags of 80 lb mix per hole.
Sources
- [1]QUIKRETE, Concrete Mix No. 1101 data sheet (bag yields) (current data sheet)
- [2]QUIKRETE, Project: Setting Posts (project sheet, checked October 5, 2026)
- [3]ConcreteNetwork.com, Concrete Prices (updated July 14, 2026)
Prices are national ranges published by the sources above, not quotes. Your price depends on size, access, site preparation and local labor rates. The only way to know is to compare written quotes.