BuildCalc Guides · Concrete
How Many Bags of Concrete for a 10×10 Slab?
A 10 by 10 foot concrete slab — patio, shed pad, hot-tub base or small structure footprint — is one of the most common DIY concrete jobs. Here is the short answer and exactly how to get there.
The math
Concrete is sold and ordered in cubic yards, but the math starts in cubic feet. For a 10 by 10 foot slab at 4 inches thick:
- Volume in cubic feet = length × width × depth, all in feet. 10 × 10 × (4 ÷ 12) = 33.33 ft³.
- Cubic yards = cubic feet ÷ 27. 33.33 ÷ 27 = 1.23 yd³ of net concrete.
- Add waste. A 5 percent allowance covers spillage and uneven subgrade — the safe minimum. 1.23 × 1.05 = 1.30 yd³ to order in bulk.
- Convert to bags. An 80 lb bag yields about 0.6 ft³, and a 60 lb bag about 0.45 ft³. With the 5 percent waste folded in, that is 59 bags of 80 lb or 78 bags of 60 lb.
By slab thickness
A 10×10 slab is built at 3, 4 or 6 inches depending on what rolls or sits on it. The bag count scales directly with depth:
| Thickness | ft³ | yd³ | 80 lb bags | 60 lb bags |
|---|---|---|---|---|
| 3" | 25.0 | 0.93 | 44 | 59 |
| 4" | 33.3 | 1.23 | 59 | 78 |
| 6" | 50.0 | 1.85 | 88 | 117 |
Includes a 5 percent waste factor and rounds up to whole bags.
Bags or ready-mix delivery?
At about 1.3 cubic yards, a 10×10 by 4 inch slab sits right on the line between bag-mixing and ready-mix territory. Here is how the trade-off shakes out:
- Bags win when access is the problem (a truck cannot reach the site), the job is under about 1 yd³, or you want to pour in stages over a couple of weekends. The downside: mixing 59 bags by hand or in a wheelbarrow mixer is real work — figure 4 to 6 hours with a buddy.
- Ready-mix wins on price and time once you are over about 1 yd³. Most suppliers charge a short-load fee under 3 yd³, but the all-in cost is still usually cheaper than 59 bags. A 1-yard pour from a truck takes about 30 minutes once it arrives.
What changes the number
- Waste factor. 5 percent is the minimum. Rough or hand-dug subgrade can push it to 10 percent — about three extra bags of 80 lb.
- Thickened edges or footings. A turn-down edge for a free-standing slab can add 10 to 20 percent of volume. Treat it as a separate pour in the calculator.
- Bag yield variance. 0.6 ft³ per 80 lb bag is the manufacturer typical for Quikrete and Sakrete concrete mix. Check the spec on the actual bags you buy — premium and fast-set mixes can differ.
Calculate for your own slab
The numbers above are for a standard 10′ × 10′ × 4″ pad. For any other size, depth or bag — including footings and round sonotube columns — BuildCalc's concrete calculator handles mixed-unit input, waste factor and live material cost.
Open the concrete calculator →FAQ
How many cubic yards of concrete is a 10x10 slab?+
A 10 by 10 foot slab at 4 inches thick is about 1.23 cubic yards of net concrete. Add a 5 percent waste allowance and you would order about 1.30 cubic yards.
How thick should a 10x10 concrete slab be?+
4 inches is the standard thickness for a patio, shed pad or other light-load slab. Go up to 6 inches for a driveway, hot-tub pad or anywhere a vehicle will sit. 3 inches is reserved for sidewalks, paver bases and other very light-duty surfaces.
Should I use 60 lb or 80 lb bags for a 10x10 slab?+
80 lb bags mean fewer bags to mix and carry, which adds up fast at this volume — 59 bags vs. 78 bags for a 4 inch slab. 60 lb bags are lighter to handle but you make more trips. For a 10x10 most people pick 80 lb to keep the count down.
Is bagged concrete cheaper than ready-mix for a 10x10 slab?+
At about 1.3 cubic yards, bagged usually ends up more expensive once you factor in 59 bags vs. a short-load delivery. Bagged still wins when the truck cannot reach the site, you need to pour in stages, or you want to do it over a weekend. For one continuous pour at this volume, ready-mix is generally faster and cheaper.
How much waste should I add for a concrete slab?+
Add at least 5 percent — that covers normal spillage and minor over-excavation. Rough or hand-dug subgrade can push it to 10 percent. The bag count and yardage shown above already include a 5 percent allowance.
Do I need rebar in a 10x10 concrete slab?+
For a 4 inch patio or shed pad, a sheet of welded wire mesh or #3 rebar at 16 to 24 inch on-center is standard practice — it does not add slab strength so much as control cracking. For driveways and heavier slabs, #4 rebar at 12 to 16 inch on-center is the usual call.
Related guides
- How to calculate stair stringers — math, IRC code limits and a worked example.
- How many bags of concrete for a fence post? — cylinder math for round post holes.
- How much paint for a 12×12 room? — wall area, doors/windows and coats.
Related calculators
- Gravel calculator — for the compacted base under the slab.
- Square footage calculator — area in feet, yards, meters and acres.