How Many Bags of Concrete Do I Need for a 10x10 Slab
If you are planning a 10x10 slab and want to mix your own concrete, the key question is how many bags to buy. This guide gives exact 80-pound and 60-pound bag counts for a 10x10 slab at common thicknesses, with a 10% waste allowance already built in.
The basic bag math
One 80-pound bag yields about 0.6 cubic feet of finished concrete, and a 60-pound bag yields about 0.45 cubic feet. Multiply your slab area by its thickness in feet, divide by the yield per bag, then add 10% for waste, spillage, and uneven subgrade.
Bag counts by thickness
| Thickness | Volume (cu ft) | 80lb bags (10% waste) | 60lb bags (10% waste) |
|---|---|---|---|
| 4 inches | 33.3 | 62 | 83 |
| 5 inches | 41.7 | 77 | 103 |
| 6 inches | 50.0 | 92 | 123 |
A 4-inch slab is the standard for patios and shed floors, so 62 bags of 80lb mix is the number most DIYers need. Always round up to whole bags — you cannot order a fraction of a bag at the store.
What it costs to bag it yourself
At $4–$6 per 80-pound bag, 62 bags runs about $248–$372 in material. Compare that with ready-mix: a 10x10 at 4 inches is about 1.36 cubic yards, which costs roughly $150–$224 delivered at $110–$165 per yard. Bagging is more expensive per yard but avoids delivery minimums and is far easier for a solo weekend project.
When bags make sense
- Small pads: Steps, landings, and post footings where a full truck is impractical.
- Repairs: Patching and topping where you only need a few bags.
- Remote sites: Where a mixer truck cannot reach, a bags-and-mixer approach wins.
If your project needs more than about one cubic yard of concrete, switch to ready-mix. The per-yard savings and the labor you avoid usually outweigh the delivery fee.
Use the calculator
Our Concrete Slab Calculator computes bag counts for 40, 60, and 80-pound bags at any size and thickness. For block or brick work around the same project, see the Block Calculator and Brick Calculator, or browse every tool on the Concrete & Masonry hub.
Mixing and buying tips
Buy bags from a home center that lets you return unopened pallets, so you are not stuck with leftovers. Open bags absorb moisture and harden, so only open what you will use within the hour. A portable mixer saves your back on anything past a dozen bags; for 60 or more bags, renting a mixer or switching to ready-mix is usually worth it.
- Add water slowly: Too much water weakens the mix and causes cracking. Follow the ratio printed on the bag.
- Keep a steady pace: Concrete begins to set in about 30–45 minutes in warm weather, so stage your pours.
- Cure it: Keep the slab moist and covered for several days; proper curing is what gives concrete its full strength.
Odd shapes and slopes
For an L-shape or curved pad, break the area into rectangles, compute each, and add the volumes together before applying the 10% waste factor. On a sloped site, use the average thickness rather than the thin edge, and round up — it is cheaper to have a little extra than to run short mid-pour.