Guide · Concrete
How Many 80 Lb Bags of Concrete Are in a Yard?
45. One cubic yard of concrete takes 45 eighty-pound bags at the standard 0.60-cubic-foot yield printed on most US bags. The math is simple: a cubic yard is 27 cubic feet, and 27 ÷ 0.60 = 45 exactly.
Below: the step-by-step math, charts for 60-lb and 40-lb bags, a partial-yard quick reference, and how many bags common projects actually need. To convert any project to yards and bags automatically, use our free concrete calculator.
Enter any slab, wall, footing, or column — get cubic yards and 40-, 60-, and 80-lb bag counts.
Open the concrete calculator →Also: 60 × 60-lb bags and 90 × 40-lb bags per cubic yard.
The math, step by step
= 27 ÷ 0.60 = 45
- A cubic yard is 27 cubic feet. Picture a 3 × 3 × 3 ft cube.
- An 80-lb bag yields about 0.60 ft³ of cured concrete. This is the number that matters — check the bag, because everything flows from it.
- Divide. 27 ÷ 0.60 = 45 bags. No rounding needed — it lands exactly on 45.
- Add waste on top. 45 × 1.10 = 49.5, so round up to 50 bags to order for a true one-yard pour.
Bags per cubic yard by bag size
| Bag size | Yield per bag | Bags per cubic yard |
|---|---|---|
| 40 lb | 0.30 ft³ | 90 |
| 60 lb | 0.45 ft³ | 60 |
| 80 lb | 0.60 ft³ | 45 |
Yields are the standard figures printed on US concrete-mix bags; specialty and fast-setting mixes can differ — read the label.
Partial-yard quick reference (80-lb bags)
| Concrete needed | Cubic feet | 80-lb bags (rounded up) |
|---|---|---|
| ¼ yard | 6.75 | 12 |
| ½ yard | 13.5 | 23 |
| ¾ yard | 20.25 | 34 |
| 1 yard | 27 | 45 |
| 1½ yards | 40.5 | 68 |
| 2 yards | 54 | 90 |
Why the number can vary
Two things move the number: the yield on your specific bag and the mix type. Most US 80-lb concrete-mix bags state 0.60 ft³, but always read the label — some high-strength or fast-setting mixes differ slightly. And mortar mix is not concrete mix: it’s formulated for laying block and brick, with different yield and strength, so don’t use its numbers for a slab. None of the figures above include waste — spillage, over-excavation, and uneven forms eat a few percent on every real pour.
How many bags do common projects need?
| Project | Volume | 80-lb bags |
|---|---|---|
| Fence post hole, 12″ diameter × 36″ deep | 2.36 ft³ | 4 |
| 4×4 slab, 4″ thick | 5.33 ft³ | 9 |
| Footing, 2×2×1 ft | 4.0 ft³ | 7 |
| 10×10 slab, 4″ thick | 33.3 ft³ | 56 (62 with waste) |
Post-hole math subtracts nothing for the post itself — the displacement is small and acts as a built-in waste allowance.
Footing example: bags for a linear run
Footings are where bag math meets linear feet. Take a 40-ft run of footing, 16 inches wide and 8 inches deep: 40 × (16÷12) × (8÷12) = 35.56 ft³; 35.56 ÷ 0.60 = 59.3, round up to 60 bags — 66 with a 10% allowance. At that quantity, price both options: 66 bags is a pallet and a half of hauling and mixing, while a short-load ready-mix truck does it in one pour. This is exactly the crossover zone where the per-bag convenience stops paying.
When 45 bags means “order ready-mix”
Forty-five 80-lb bags weigh 3,600 lb — nearly two tons — and that’s before water, mixing, and placing against the clock. Anything approaching a full yard is firmly in ready-mix or tow-behind-mixer territory for most DIYers. Bags shine for sub-yard jobs: post holes, small pads, stair repairs, and setting posts.
From project dimensions to bag count
Three steps, no calculator required: (1) compute cubic feet (length × width × thickness, all in feet); (2) divide by 27 for cubic yards; (3) multiply yards by 45. Example — a 4×8 ft pad at 4 inches thick: 4 × 8 × (4÷12) = 10.67 ft³; 10.67 ÷ 27 = 0.40 yd³; 0.40 × 45 = 17.8, round up to 18 bags (20 with a 10% allowance). Or skip the yard step entirely: 10.67 ÷ 0.60 = 17.8 → 18 bags. Same answer either way.
Choosing the right bag: concrete mix vs. mortar vs. fast-setting
Not every bag on the pallet aisle is interchangeable. Concrete mix contains cement, sand, and gravel aggregate — it’s the structural stuff for slabs, footings, and post holes, and it’s what every number on this page assumes. Mortar mix has no large aggregate; it’s formulated for laying block, brick, and stone, with different yield and strength — don’t substitute it for a slab. Fast-setting concrete mix is for setting posts: pour it dry into the hole, add water, and it sets in 20–40 minutes with no mixing. It costs more per bag, but for a handful of post holes it saves hours. High-strength mixes (often labeled 5000 PSI) suit heavy loads and structural work — same bag math, higher price. Whatever you buy, the 45-bags-per-yard figure holds as long as the label says 0.60 ft³ yield — check before you count.
Buying and hauling: pallets, weight, and storage
Forty-five bags weigh 3,600 lb — check your vehicle’s payload rating before you load up, because most half-ton pickups can’t legally carry that in one trip. Bags are sold by the pallet: a standard pallet holds 42 eighty-pound bags (3,360 lb), which at 0.60 ft³ per bag is 25.2 ft³ — just short of a full yard. So a one-yard job needs a pallet plus 3 bags, or a pallet plus 8 with a 10% waste allowance. Store bags off the ground under cover; one good rain on an open pallet ruins the cement. And buy a few extra: returning unopened bags is easy, running short mid-pour is not.
How we calculate
One cubic yard equals 27 ft³. Bags per yard = 27 ÷ per-bag yield, using standard US label yields of 0.60 ft³ (80-lb), 0.45 ft³ (60-lb), and 0.30 ft³ (40-lb). Partial-yard counts are rounded up to whole bags. Reference tables carry no waste allowance — add 5–10% when ordering. Project volumes use the rectangular-prism formula, or πr²h for round post holes.
Reviewed September 2026 · TrueMeasure
Frequently asked questions
Is it exactly 45 bags per cubic yard?
At the standard 0.60 ft³ yield, yes — 27 ÷ 0.60 = 45 exactly. If your bag’s label states a different yield, divide 27 by that number instead.
How many 60-lb bags of concrete are in a yard?
60. A 60-lb bag yields about 0.45 ft³, and 27 ÷ 0.45 = 60.
How many 40-lb bags of concrete are in a yard?
90. A 40-lb bag yields about 0.30 ft³, and 27 ÷ 0.30 = 90.
How much water does an 80-lb bag of concrete need?
About 3 quarts per 80-lb bag for standard concrete mix — but follow the bag’s instructions exactly. Too much water weakens the concrete; add water gradually and mix to a workable, not soupy, consistency.
Can I mix a full cubic yard by hand?
Not practically — 45 bags is 3,600 lb of dry material. Use a powered mixer for half-yard jobs and call ready-mix at around a yard and up.
How many bags do I need for a 10×10 slab?
56 eighty-pound bags at 4 inches thick (62 with 10% waste). See the full breakdown in our 10×10 slab guide.