How Many Bags of Concrete Are in a Cubic Yard?
The numbers
| Bag size | Yield per bag | Bags per cubic yard | Weight per yard |
|---|---|---|---|
| 80 lb | 0.60 cu ft | 45 | 3,600 lb |
| 60 lb | 0.45 cu ft | 60 | 3,600 lb |
| 50 lb | 0.375 cu ft | 72 | 3,600 lb |
| 40 lb | 0.30 cu ft | 90 | 3,600 lb |
Every row weighs the same, which is the useful part: a cubic yard of concrete is about 3,600 lb of dry mix no matter how you package it. Choosing a smaller bag does not reduce the work, it just splits it into more trips up the driveway.
Where 27 comes from
A cubic yard is a cube one yard on each side. A yard is three feet, so the volume is 3 × 3 × 3 = 27 cubic feet. That constant is worth memorising, because it converts between the unit concrete is quoted in and the unit bags are labelled in.
From there the bag count is one division, always rounded up:
bags = 27 ÷ bag yield → 27 ÷ 0.60 = 45 bags of 80 lb mix.
Why the bag says pounds but yields cubic feet
Concrete mix is sold by weight because that is how it is batched and shipped, but it is used by volume. The yield printed on the bag — 0.60 cu ft for a standard 80 lb bag of pre-mixed concrete — already accounts for the water you add: mixing does not meaningfully change the volume, because water fills voids between the aggregate rather than adding to the pile.
Two cautions on that number. High-strength and fast-setting mixes use different aggregate gradations and can yield slightly less per pound, and a bag stored outdoors that has taken on moisture is heavier without yielding more. Always take the yield from the bag in front of you when the job is close to a bag-count boundary.
What a cubic yard actually covers
| Thickness | Coverage per cubic yard | Typical use |
|---|---|---|
| 2 in | 162 sq ft | Topping slab, thin overlay |
| 4 in | 81 sq ft | Patio, walkway, shed pad |
| 5 in | 65 sq ft | Driveway, light vehicle |
| 6 in | 54 sq ft | Driveway with heavy vehicles |
| 8 in | 40 sq ft | Garage slab, footing pad |
The point where bags stop making sense
The practical limit is not cost, it is time. Concrete begins to stiffen within 30 to 90 minutes of mixing depending on temperature, and a slab has to be placed as one continuous pour if you want a monolithic result rather than a cold joint. A single person with one mixer can realistically place about half a cubic yard before the first batch is beyond working.
So the honest rule is:
- Under half a yard (about 22 bags of 80 lb): bags, one person, no problem.
- Half to one yard: bags, but get help and a second mixer, or accept a construction joint.
- Over one yard: call the ready-mix supplier. Most have a one-yard minimum and add a short-load fee under three or four yards, and that fee is usually cheaper than the labour and the risk of a cold joint.
Do not forget the waste allowance
Bag counts computed from a drawing are always optimistic. The subgrade is never perfectly flat, forms bow outward slightly under the weight of wet concrete, and some mix is left in the mixer and on the ground. Add 10% for a formed slab on prepared gravel, and 15–20% for trenches and hand-dug post holes, where the excavation is wider at the bottom than you think.
Work out how much concrete a pour needs in cubic yards — then see the same volume as 80, 60, 50 and 40 lb bags so you can compare bagged mix against a ready-mix delivery before you order.
Frequently asked questions
How many 80 lb bags make a cubic yard?
Forty-five. An 80 lb bag yields 0.60 cubic feet and a cubic yard is 27 cubic feet.
How much does a cubic yard of concrete weigh?
About 3,600 pounds as dry bagged mix, and roughly 4,000 pounds once mixed with water — close to two tons either way, which is why ready-mix trucks are built the way they are.
Can one person pour a cubic yard from bags?
It is possible but not advisable. Forty-five bags is 3,600 pounds to carry, open and mix, and the first batches will start to stiffen before the last are placed, leaving cold joints through the slab. Half a cubic yard is a more realistic solo limit.
- How Thick Should a Concrete Slab Be?
- How Many Bags of Concrete per Fence Post?
- How Long Does Concrete Take to Cure?
- What Drives the Cost of a Concrete Patio?