Concrete
How Many Bags of Concrete Are in a Yard?
One cubic yard of concrete takes about 45 bags of 80 lb concrete mix or 60 bags of 60 lb, based on QUIKRETE Concrete Mix yields of 0.60 ft³ and 0.45 ft³ per bag.
By Kumar Baniya, MEng in Structural Engineering (University of Leeds) · Published
How many 80 lb bags of concrete make a yard?
45 bags. A cubic yard is 27 cubic feet, and an 80 lb bag of QUIKRETE Concrete Mix yields about 0.60 ft³ of mixed concrete, so 27 ÷ 0.60 = 45. With 60 lb bags (0.45 ft³ each) you need 60 bags.
These counts are for one product. Other mixes and brands state different yields, so check the yield printed on the bag you buy.
How many bags of each size make a cubic yard?
The table divides 27 ft³ by the manufacturer’s stated yield for each QUIKRETE Concrete Mix (No. 1101) bag size and rounds up to whole bags.
| Bag weight | Approximate yield | Bags per cubic yard | Bags per cubic foot |
|---|---|---|---|
| 80 lb | 0.6 ft³ | 45 | 1.67 |
| 60 lb | 0.45 ft³ | 60 | 2.22 |
| 50 lb | 0.375 ft³ | 72 | 2.67 |
| 40 lb | 0.3 ft³ | 90 | 3.33 |
| 90 lb (regional) | 0.675 ft³ | 40 | 1.48 |
Why does bag yield matter more than bag weight?
Concrete is ordered by volume, but bags are sold by weight. The yield — the volume of mixed concrete one bag makes — is what converts one into the other. Two bags of the same weight can yield different volumes if the mix is different, which is why the concrete calculator asks for the product’s yield instead of assuming one.
How do I work out bags for my own project?
- Calculate the volume in cubic feet: length × width × thickness (in feet).
- Divide by the bag’s yield in cubic feet.
- Round up to a whole bag.
Example: a 10 × 10 ft slab 4 in thick is 100 × 4 ÷ 12 = 33.33 ft³. That is 56 bags of 80 lb or 75 bags of 60 lb. The thickness here is an example for the arithmetic, not a recommendation.
If you want a margin for spillage or an uneven base, add it once to the volume before dividing — the calculator’s allowance option does this and shows it separately.
Should I buy 60 lb or 80 lb bags?
Either works: per cubic yard they add up to the same dry weight. 45 bags × 80 lb and 60 bags × 60 lb are both 3,600 lb, because the yield scales with bag weight for this mix (72 × 50 lb and 90 × 40 lb are also 3,600 lb). The difference is handling: smaller bags are lighter to lift but mean more bags to open and mix.
How many bags of concrete for a 10 × 10 slab?
A 10 × 10 ft slab is 100 sq ft; the bag count depends on thickness.
| Thickness | Volume | 80 lb bags | 60 lb bags |
|---|---|---|---|
| 3 in | 25.00 ft³ | 42 | 56 |
| 3.5 in | 29.17 ft³ | 49 | 65 |
| 4 in | 33.33 ft³ | 56 | 75 |
| 5 in | 41.67 ft³ | 70 | 93 |
| 6 in | 50.00 ft³ | 84 | 112 |
Beyond a couple of cubic yards, compare the bag total with a ready-mix quote.
How many bags of concrete for a fence post hole?
Treat the hole as a cylinder and subtract the post. A hole 10 in across and 3 ft deep holds π × (5 ÷ 12)² × 3 = 1.64 ft³. A 4 × 4 post (actually 3.5 × 3.5 in) takes up 0.26 ft³ of that, leaving 1.38 ft³ — 3 bags of 80 lb or 4 of 60 lb per hole. Hole size is an example; follow the post manufacturer’s or code requirements.
Related calculations
For the volume itself, see how to calculate yards of concrete. For large pours, bags become impractical quickly; how many yards of concrete are in a truck explains ready-mix loads.