How many bags of concrete make a cubic yard?
Short answer: 90 of the 40 lb bags, 72 of the 50 lb bags, 60 of the 60 lb bags, 45 of the 80 lb bags, 41 of the 90 lb bags. A cubic yard is 27 cubic feet, and each bag makes the volume of mixed concrete printed on it, so the count is 27 divided by that yield, rounded up to whole bags. The reason to know the number is not usually to buy a yard in bags: it is to see, quickly, whether a job is a bag job or a truck job.
The yield chart
| Bag | Yield (cu ft) | Bags per cu yd (exact) | Whole bags for 1 cu yd | Weight of those bags (lb) |
|---|---|---|---|---|
| 40 lb bag (0.30 cu ft) | 0.300 | 90.0 | 90 | 3,600 |
| 50 lb bag (0.375 cu ft) | 0.375 | 72.0 | 72 | 3,600 |
| 60 lb bag (0.45 cu ft) | 0.450 | 60.0 | 60 | 3,600 |
| 80 lb bag (0.60 cu ft) | 0.600 | 45.0 | 45 | 3,600 |
| 90 lb bag (0.67 cu ft) | 0.670 | 40.3 | 41 | 3,690 |
- QUIKRETE Concrete Mix (No. 1101) data sheet (read 2026-10-05)
- Sakrete High-Strength Concrete Mix technical data sheet (read 2026-10-05)
The yields all come to roughly the same density, which is a useful sanity check: 40 lb ÷ 0.30 cu ft = 133 lb per cubic foot; 50 lb ÷ 0.375 cu ft = 133 lb per cubic foot; 60 lb ÷ 0.45 cu ft = 133 lb per cubic foot; 80 lb ÷ 0.60 cu ft = 133 lb per cubic foot; 90 lb ÷ 0.67 cu ft = 134 lb per cubic foot. Quikrete lists the placed concrete at about 140 lb per cubic foot; the bag's dry weight is a little less because the water is added by you. Different products have different yields: fast-setting mixes, high-strength mixes and mortar mixes each print their own, and a bag of sand-topping mix is not a bag of concrete. Use the figure on the bag you are buying.
Bags for common jobs
The same arithmetic applied to jobs people actually do, each with a 10 percent allowance for an uneven subgrade and what stays in the mixer. The ready-mix column is rounded up to the quarter yard, which is how suppliers bill.
| Job | Cu ft | Cu yd | 40 lb bags | 50 lb bags | 60 lb bags | 80 lb bags | 90 lb bags | Ready-mix order |
|---|---|---|---|---|---|---|---|---|
| 4 x 8 ft pad, 4 in | 11.7 | 0.43 | 40 | 32 | 27 | 20 | 18 | 0.50 cu yd |
| 10 x 10 ft slab, 4 in | 36.7 | 1.36 | 123 | 98 | 82 | 62 | 55 | 1.50 cu yd |
| 12 x 12 ft patio, 4 in | 52.8 | 1.96 | 176 | 141 | 118 | 88 | 79 | 2.00 cu yd |
| 20 x 20 ft garage floor, 4 in | 146.7 | 5.43 | 489 | 392 | 326 | 245 | 219 | 5.50 cu yd |
| 10 post holes, 12 x 30 in, 4 x 4 posts | 19.3 | 0.71 | 65 | 52 | 43 | 33 | 29 | 0.75 cu yd |
| 4 steps, 4 ft wide, 7 in rise, 11 in run | 23.5 | 0.87 | 79 | 63 | 53 | 40 | 36 | 1.00 cu yd |
Post hole volumes have the post subtracted. The stairs are four steps stacked as solid blocks, which is how a formed-in-place stair is poured; stairs on a sloped fill use less.
Read down the 80 lb column and the pattern is clear. A pad or a set of post holes is a trip to the store. A 10 x 10 slab is already 62 of the 80 lb bags, which is a long day for two people with a mixer. A garage floor is 245 bags and nobody does that by hand.
Bags versus the truck
Both cost money and both cost effort, and the comparison has to include both.
- Bag cost is the bag count times the bag price, plus the trip. There is no minimum, you can buy one more bag if you run short, and leftover bags keep for months if they stay dry.
- Ready-mix cost is the yards (rounded up to the quarter) times the price per yard, plus delivery, plus a short-load fee on orders below the supplier's minimum, which is often several yards. For a small pour the fees can exceed the concrete.
- Bag effort is lifting every bag twice and mixing it, at a pace of a few bags an hour per person with a drum mixer, and placing the concrete section by section before each batch sets. It is reasonable for a yard and brutal for three.
- Truck effort is having forms, base, reinforcement, help and tools ready, and placing and finishing the whole load inside the hour or so before it stiffens. The concrete arrives mixed consistently, which bags never quite manage.
With the typical prices on file ($6.15 to $6.47 per 80 lb bag as of October 2026; $119 to $147 per cubic yard of ready-mix as of January 2026, before fees), a yard in 80 lb bags costs between $277 and $291. Add your supplier's delivery and short-load fees to the truck side and compare for your yards.
Between the two there is a third option worth asking about: many supply yards rent a towable mixing trailer filled with a yard or so of wet concrete, or sell "short loads" from a smaller truck. It costs more per yard than a full truck and far less effort than bags, and for one to two yards it is often the right answer.
Getting the count right
- Measure the real thickness. A slab screeded to the top of 2 x 4 forms is 3 1/2 in, not 4, unless the forms are set up on stakes; the difference is an eighth of the concrete.
- Subtract the post from the hole. In a 12 in hole a 4 x 4 post is about a tenth of the volume. The calculator does it.
- Add 10 percent. Running out mid-pour means a cold joint and a dash for more bags.
- Use the water on the bag. The yield assumes it; a sloppy mix pours easily, yields a little more and cracks early.
- Round ready-mix up. Suppliers bill in quarter yards and will not return with a quarter.
Related
- Concrete calculator, for slabs, footings, post holes, columns and stairs
- Fence calculator, for the concrete per post across a whole fence
- How the estimates are calculated