How Many Bags of Concrete Do You Need for a 10×10 Slab?
Calculate exactly how many 80-lb, 60-lb, or 40-lb bags you need for a 10×10 concrete slab.
A 10×10 foot slab at 4 inches thick takes about 1.24 cubic yards of concrete. If you're mixing bags by hand, that's roughly 56 bags of 80-lb mix, 75 bags of 60-lb, or 112 bags of 40-lb.
That's a lot of bags. And honestly, once you get past about 40 bags, you should seriously think about just ordering a yard of ready-mix from your local batch plant. Mixing that many bags with a wheelbarrow and a hoe is brutal work, and the concrete starts setting before you finish if you're not fast enough.
The Math
The formula is dead simple:
Length × Width × Depth = Cubic Feet
10 × 10 × 0.33 (that's 4 inches converted to feet) = 33.3 cubic feet
Divide by 27 to get cubic yards: 33.3 ÷ 27 = 1.23 cubic yards
Most people round up to 1.24 because you always want a little extra. Running short on a pour is one of the worst things that can happen on a concrete job — you end up with a cold joint that's going to crack.
Bags vs. Ready-Mix
Here's the breakdown for a 10×10 slab at 4 inches:
| Bag Size | Yield per Bag | Bags Needed | |----------|--------------|-------------| | 80 lb | 0.6 cubic ft | 56 | | 60 lb | 0.45 cubic ft | 75 | | 40 lb | 0.3 cubic ft | 112 |
An 80-lb bag runs about $5–$7 at Home Depot or Lowe's. So 56 bags costs you $280–$392 just for the concrete. Plus your back will hate you.
A cubic yard of ready-mix delivered by truck? Usually $125–$175 per yard depending on your area. For 1.24 yards, that's around $155–$217 total. Way cheaper, way faster, and the truck does the heavy lifting.
The catch is most concrete companies have a minimum order — often 1 yard — and some charge a short-load fee for anything under 3-4 yards. Still worth calling. Even with the short-load fee, it usually beats mixing 56 bags.
What About a 6-Inch Slab?
If you're pouring a driveway or garage floor, 4 inches isn't enough. You want 6 inches minimum for anything that's going to support vehicles.
A 10×10 slab at 6 inches takes 1.85 cubic yards — about 84 bags of 80-lb mix. At that point, there's no question — order ready-mix.
Don't Forget the Extra 10%
Always order at least 10% more than your calculation says. The ground is never perfectly flat, your forms might bow a little, and you'll spill some. On a 1.24 yard job, round up to about 1.4 yards. Nobody ever complained about having a little extra concrete, but coming up short mid-pour can ruin the whole job.
Use our free concrete calculator to get exact numbers for your specific project dimensions.
Frequently Asked Questions
- How many 80-lb bags of concrete do I need for a 10×10 slab at 4 inches thick?
- You need about 56 bags of 80-lb concrete mix for a 10×10 slab at 4 inches thick. That's 1.23 cubic yards total. At that quantity, calling a ready-mix supplier for a small truck delivery is usually cheaper and far less labor.
- Is it cheaper to use bags or ready-mix concrete for a 10×10 slab?
- Ready-mix is usually cheaper for a 10×10 slab. Fifty-six bags of 80-lb mix cost $280–$392, while 1.24 yards of ready-mix typically runs $155–$217 delivered. Ready-mix also saves several hours of hand-mixing work.
- What thickness should a 10×10 concrete slab be?
- For a patio or shed floor, 4 inches is standard. For a garage floor or anything supporting vehicle weight, go 6 inches minimum. A 10×10 slab at 6 inches needs about 1.85 cubic yards (84 bags of 80-lb mix).
- Do I need rebar in a 10×10 concrete slab?
- For a lightly loaded patio or shed floor, wire mesh (6×6 W1.4×W1.4) is common and cheaper than rebar. For a garage slab or any slab that will support heavy loads, use #3 rebar on 18-inch centers. Either way, support it in the middle of the slab thickness, not on the ground.
- How much does a 10×10 concrete slab cost to pour?
- Materials alone run $150–$400 depending on whether you use bags or ready-mix. If you hire a contractor, expect $500–$1,500 total for a 10×10 slab including labor, forming, and finishing — with significant regional variation.
- Why should I order 10% extra concrete?
- The ground is rarely perfectly flat, forms can bow slightly under pressure, and some concrete always spills or sticks to equipment. Running short mid-pour is a serious problem — you get a 'cold joint' where fresh concrete meets partially-set concrete, which almost always cracks. Order 10% extra as insurance.