How Many 60 lb Bags of Concrete Do I Need?
Quick answer: a 60 lb bag makes about 0.45 cubic feet of concrete, so you need roughly 60 bags per cubic yard. For a 10×10 slab at 4 inches deep, that's about 74 bags before waste, or ~82 with 10% waste.
- How much a 60 lb bag makes
- Cubic yards to bags
- Quick lookup: common sizes
- 60 lb vs 80 lb bags
- Worked example: a 10×10 slab
- FAQ
How much a 60 lb bag makes
A standard 60 lb bag of concrete mix yields about 0.45 cubic feet of wet concrete. That's the number you need for the math. The mix's label also lists coverage at a given thickness — for example, about 1.35 sq ft at 4 inches thick per bag.
Cubic yards to bags
One cubic yard is 27 cubic feet. Divide by the bag yield:
60 lb bag → 0.45 cu ft → about 60 bags per cubic yard
80 lb bag → 0.60 cu ft → about 45 bags per cubic yard
40 lb bag → 0.30 cu ft → about 90 bags per cubic yard
Quick lookup: common sizes
| Job | Volume | 60 lb bags | 80 lb bags |
|---|---|---|---|
| 8×8 pad @ 4 in | 0.79 cu yd | ~48 | ~35 |
| 10×10 slab @ 4 in | 1.23 cu yd | ~74 | ~55 |
| Post footing (1 ft deep) | ~0.1 cu yd | ~6 | ~4.5 |
| 20×20 driveway @ 5 in | 6.2 cu yd | ~372 | ~279 |
For anything much beyond a few bags, ready-mix (delivered by truck) is cheaper per cubic yard and saves the mixing.
60 lb vs 80 lb bags
Both are common. A 60 lb bag is lighter (easier to carry and mix by hand) but means more bags for the same volume. An 80 lb bag has a slightly lower per-bag cost per cubic foot and fewer bags to haul, but is heavier and harder for one person to manage. For a small pad or a handful of footings, 60 lb bags are the practical pick; for a big slab, consider 80 lb or ready-mix.
Worked example: a 10×10 slab
- Area = 10 × 10 = 100 sq ft
- Depth = 4 in = 0.333 ft → volume = 100 × 0.333 = 33.3 cu ft = 1.23 cu yd
- 60 lb bags = 33.3 ÷ 0.45 = ~74 bags
- Plus 10% waste → ~82 bags
- That's a lot of mixing — for a slab this size, quote ready-mix too
FAQ
One cubic yard is 27 cubic feet, and a 60 lb bag makes about 0.45 cubic feet — so you need about 60 bags of 60 lb mix per cubic yard. Add waste on top.
A 10×10 slab at 4 inches deep is about 1.23 cubic yards. At 0.45 cu ft per 60 lb bag, that's roughly 74 bags before waste, or about 82 with 10% waste.
It depends on what you can handle. A 60 lb bag is lighter and easier to mix and carry; an 80 lb bag means fewer bags and less per-bag cost but is heavier. For big slabs, 80 lb bags reduce the bag count.
A 60 lb bag covers about 1.8 square feet at 3 inches thick, 1.35 square feet at 4 inches, and 1 square foot at 6 inches. Divide your area by these numbers for the bag count.