How Many Bags of Concrete Are in a Cubic Yard?
A cubic yard is 27 cubic feet, so the answer depends only on the bag: 45 bags of 80 lb, 60 bags of 60 lb, or 90 bags of 40 lb. Here is the table, two worked examples and when ready-mix beats bags.
How many bags make a cubic yard?
Concrete bag yields are printed on the bag, and they are the only numbers that matter here. A standard 80 lb bag of pre-mixed concrete yields 0.60 cubic feet; a 60 lb bag yields 0.45; a 40 lb bag yields 0.30. Since a cubic yard is 27 cubic feet, dividing gives the bag count:
| Bag size | Yield per bag | Bags per cubic yard |
|---|---|---|
| 40 lb | 0.30 ft³ | 90 |
| 50 lb | 0.375 ft³ | 72 |
| 60 lb | 0.45 ft³ | 60 |
| 80 lb | 0.60 ft³ | 45 |
Round up, and add 5% for spillage and uneven subgrade. Bags are convenient but heavy: 45 bags of 80 lb is 3,600 lb of material, which is why most projects over a cubic yard switch to ready-mix.
Worked example: a 10 × 10 ft slab at 4 inches
Volume = 10 × 10 × (4 ÷ 12) = 33.3 ft³ = 1.23 cubic yards. At 45 bags per yard that is 56 bags of 80 lb (or 74 bags of 60 lb). Add 5% and buy 59 bags.
For a footing or a post hole the arithmetic is the same, just with a cylinder: π × radius² × height. A 12 inch diameter hole 3 ft deep holds π × 0.5² × 3 = 2.36 ft³, which is 4 bags of 80 lb.
Bags versus ready-mix
One cubic yard of ready-mix is about 45 bags of 80 lb. Ready-mix arrives mixed, in the right slump, and you have a limited time to place it — usually 60–90 minutes. Bags are slower, need a mixer or a wheelbarrow and a strong back, but you can work at your own pace and buy in small increments.
Rule of thumb: under half a cubic yard, bags win. Between half a yard and a yard, it depends on access and how many people are helping. Over a yard, ready-mix is almost always the better deal once you count the bags, the mixing and the time.
Getting the mix right
Use the water printed on the bag, not "until it looks right". Extra water is the single most common reason a small pour ends up weak and dusty. Mix in a wheelbarrow or a drum mixer, add water gradually, and stop at a consistency like thick oatmeal. For slabs, rod or vibrate the concrete to remove air pockets, then float and trowel the surface.
FAQ
- How many 80 lb bags of concrete are in a yard?
- 45 bags at 0.60 cubic feet each. Buy 47–48 to cover spillage.
- How much concrete does one bag make?
- An 80 lb bag makes about 0.60 cubic feet, roughly enough for a 2 ft × 2 ft patch at 2 inches deep.
- Can I mix bags in a wheelbarrow?
- Yes for one or two bags at a time. Beyond that a drum mixer is faster and gives a more consistent mix.
- How long before I can walk on it?
- Usually 24 hours for foot traffic and 7 days before vehicles, depending on temperature and mix.