How Many Bags of Concrete in a Yard?
A cubic yard of concrete is 27 cubic feet, so it takes about 45 bags of 80 lb mix, 60 bags of 60 lb, or 90 bags of 40 lb to fill it. Here is where those numbers come from, a quick table by bag size, and the point where buying bags stops making sense and ready-mix wins.
Key takeaways
- One cubic yard equals 27 cubic feet: divide 27 by a bag's yield to get the count.
- 80 lb bags (0.60 ft³ yield) need about 45 per yard; 60 lb needs 60; 40 lb needs 90.
- A 10x10 ft slab at 4 inches takes about 56 bags of 80 lb mix, or 62 once you add a 10% waste buffer.
- Above about 1 cubic yard, ready-mix delivered is cheaper than bags once labor is counted.
Start with the cubic yard
Concrete delivered by truck is sold by the cubic yard: a cube three feet on each side. Three times three times three is 27, so one cubic yard equals 27 cubic feet.
Bagged concrete is sold by weight, and each bag lists the volume it makes once you add water. To go from bags to a yard, divide 27 by the yield of one bag.
Bags per yard by bag size
The yield printed on standard pre-mixed concrete is about 0.60 cubic feet for an 80 lb bag, 0.45 for a 60 lb bag, and 0.30 for a 40 lb bag. Divide 27 by each yield and you get the bags it takes to make a full cubic yard.
| Bag size | Yield per bag | Bags per cubic yard |
|---|---|---|
| 80 lb | 0.60 ft³ | 45 |
| 60 lb | 0.45 ft³ | 60 |
| 50 lb | 0.375 ft³ | 72 |
| 40 lb | 0.30 ft³ | 90 |
So the short answer most people want is about 45 bags of 80 lb concrete per cubic yard. The smaller the bag, the more of them you need, and the more mixing and lifting the job becomes.
How many bags for your pour
You rarely need a full yard. The more useful question is how many bags your actual pour takes. Find the volume in cubic feet, then divide by the bag yield.
A 10 by 10 foot slab at 4 inches thick is about 33.3 cubic feet, which is roughly 56 bags of 80 lb mix, or 62 bags with a 10% waste allowance. A few sonotube piers might need only a handful, while a driveway runs into the hundreds.
Rather than work each one out by hand, the concrete calculator gives the 40, 60 and 80 lb bag counts for any slab, footing, column or set of stairs, with the waste already built in.
When bags stop making sense
Bags are convenient for small jobs: a few post holes, a small pad, a repair. But the labor adds up fast. Mixing 45 bags by hand or in a small mixer to make a single cubic yard is heavy, slow work, and quality varies batch to batch because each mix is slightly different.
As a rule of thumb, once a pour passes about one cubic yard, ready-mix delivered is cheaper and far less work than buying bags. Forty-five bags cost more than a yard of ready-mix in most areas once you factor in your time. The calculator flags this for you and recommends ready-mix above roughly a cubic yard.
Bags versus ready-mix on cost
An 80 lb bag runs a few dollars in 2026, so 45 of them to fill a cubic yard adds up to well over a hundred dollars in materials, before labor. Ready-mix delivered runs roughly $125 to $160 per cubic yard, though short-load fees apply below about a full truck.
For one or two yards the two options are close on materials, but ready-mix wins on time and consistency. For under half a yard, bags usually win because a short load carries a delivery premium.
Let the calculator count the bags
Counting bags by hand is easy to get wrong with the 0.60, 0.45 and 0.30 cubic foot yields and a waste factor on top. Enter your dimensions in the concrete calculator and it returns the exact number of 40, 60 and 80 lb bags, the cubic yards, whether to switch to ready-mix, and an optional cost estimate.
For a slab specifically, the concrete slab calculator handles the same math with a slab-shaped form and gives a printable summary you can take to the store.