Worked example
How Much Concrete for a 10x10 Slab?
This example uses a 10 ft by 10 ft slab at 4 in thick and shows volume plus bag count using your selected bag yield. The quick-answer table below covers 4 in, 6 in, and 8 in thickness using the site's bag yield presets.
Quick answer
59 80 lb bags is the default estimate for a 10x10 slab at 4 in thick with 5% waste. The same calculator output is 35.00 cu ft, or about 1.30 cu yd after waste. If you switch bag size, use 78 60 lb bags or 117 40 lb bags.
Calculator inputs
Concrete Slab Calculator Results
Results update in your browser as you edit inputs. They are planning estimates, not complete shopping lists.
Enter project dimensions to calculate material quantity.
Concrete for a 10x10 slab by thickness
All rows use a 10 ft by 10 ft slab (100 sq ft) with a 5% waste factor. Bag counts are rounded up. Bag yields: 40 lb bag = 0.30 cu ft; 60 lb bag = 0.45 cu ft; 80 lb bag = 0.60 cu ft.
| Thickness | Cubic feet (after 5% waste) | Cubic yards (after 5% waste) | 40 lb bags | 60 lb bags | 80 lb bags |
|---|---|---|---|---|---|
| 4 in | 35.00 cu ft | 1.30 cu yd | 117 bags | 78 bags | 59 bags |
| 6 in | 52.50 cu ft | 1.94 cu yd | 175 bags | 117 bags | 88 bags |
| 8 in | 70.00 cu ft | 2.59 cu yd | 234 bags | 156 bags | 117 bags |
These figures use the preset bag yields from the concrete slab calculator. Use the yield printed on your actual product label when it differs.
Inputs used in this example
- Slab size: 10 ft by 10 ft.
- Thickness: 4 inches.
- Bag yield: 0.6 cubic feet per bag (80 lb bag preset).
- Waste factor: 5%.
Expected output
The calculator estimates 33.33 cubic feet before waste, 35 cubic feet after 5% waste, about 1.30 cubic yards after waste, and about 59 bags at 0.6 cubic feet per bag.
When to adjust this example
- Increase waste for uneven excavation, overdig, or forms that are not square.
- Use the bag yield printed on the product you plan to buy.
- At 6 inches thick, this same 10x10 slab needs about 88 bags with 5% waste; at 8 inches thick, about 117 bags.
- This example does not include forms, reinforcement, base material, permits, or finishing supplies.
Formula explanation
- Convert 4 inches to 0.333 feet.
- Multiply length x width x thickness to get cubic feet: 10 x 10 x 0.333 = 33.33 cu ft.
- Apply the 5% waste factor: 33.33 x 1.05 = 35.00 cu ft.
- Divide cubic feet by 27 to get cubic yards: 35.00 / 27 = 1.30 cu yd.
- Divide waste-adjusted cubic feet by bag yield and round up: 35.00 / 0.60 = 58.33, rounds to 59 bags.
Main calculator
Use the full Concrete Slab Calculator to change dimensions, waste factor, and optional user-entered unit price.
FAQ
Can this replace a ready-mix quote?
No. It estimates material quantity only and does not provide live prices or contractor quotes.
Where do I find bag yield?
Use the yield printed on the concrete bag you plan to buy.
How many 80 lb bags for a 10x10 slab at 4 inches thick?
Using an 80 lb bag yield of 0.60 cu ft and a 5% waste factor, the estimate is 59 bags. The slab volume is 35 cu ft after waste, and 35 / 0.60 rounds up to 59.
How many 60 lb bags for a 10x10 slab at 4 inches thick?
Using a 60 lb bag yield of 0.45 cu ft and a 5% waste factor, the estimate is 78 bags. The slab volume is 35 cu ft after waste, and 35 / 0.45 rounds up to 78.
Is it cheaper to use bags or ready-mix for a 10x10 slab?
This calculator does not use live prices and cannot compare costs. As a planning reference, a 10x10 slab at 4 inches thick is about 1.30 cubic yards after waste. At that volume many DIYers use bags for convenience, but at larger volumes or on tight schedules ready-mix can be more practical. Enter your own bag price to see a rough material estimate.
How much does thickness change the concrete amount?
Thickness has a direct proportional effect. Going from 4 inches to 6 inches (50% thicker) increases volume by 50%, from about 35 cu ft to about 52.5 cu ft. Going from 4 inches to 8 inches doubles the volume to about 70 cu ft. See the quick-answer table for 40 lb, 60 lb, and 80 lb bag counts at each thickness.
How many cubic yards of concrete for a 10x10 slab?
About 1.30 cubic yards for a 10x10 slab at 4 inches thick with 5% waste. Before waste, the calculator output is 33.33 cu ft, or about 1.23 cu yd; after waste it is 35.00 cu ft, or 1.30 cu yd.
Do I need gravel under a 10x10 concrete slab?
Usually plan for compacted gravel or another approved base under a slab, especially over soil that drains poorly or may move. This example estimates concrete only; check local code, soil conditions, and project type before setting base depth.
10x10 vs 12x12 slab — how much more concrete?
A 10x10 slab is 100 sq ft. A 12x12 slab is 144 sq ft — 44% more area. At the same 4-inch thickness with 5% waste, the 10x10 needs about 35 cu ft (59 bags at 80 lb) while the 12x12 needs about 50.4 cu ft (84 bags at 80 lb). That is roughly 25 more bags for the same thickness.
If you are comparing sizes, the jump from 10x10 to 12x12 adds about 44% more concrete by volume at equal thickness. Use the worked example for a 12x12 slab to see the full table.
What this estimate does and does not include
- Included: slab volume in cubic feet and cubic yards, waste-adjusted totals, bag count from selected yield.
- Not included: ready-mix delivery volume, rebar or wire mesh, vapor barrier, base gravel or compacted fill, forming lumber, permits, labor, or finishing supplies.
- No live prices are used. Any cost calculation uses only the bag price you type into the optional price field.
Planning notes for a 10x10 concrete slab
A 10 ft by 10 ft slab is a common size for a small shed foundation, utility pad, garden shed base, or AC condenser pad. The 100 sq ft area keeps the project manageable for a DIYer mixing bags by hand or with a small rented mixer, especially at 4-inch thickness.
At 4 inches thick, the slab is within the typical range for light-duty slabs without vehicle loads. At 6 inches, it is suitable for heavier sheds or light structural loads where a local code requires extra thickness. Always confirm the required thickness with your local permit office or a structural professional before pouring.
Bag mixing is practical for this slab size, but mixing 59 or more 80 lb bags is physically demanding. Plan the pour for one session and have enough help to mix and place concrete before it begins to set.
More 10x10 slab planning help
Use the 80 lb bag example when you want the bag-count answer first. Use the guide when you want more background on thickness, yield, waste, and project planning without changing this calculator example.
Related material guides
Use these guides when you want to understand the planning assumptions behind this worked example.
Compare concrete volume and bag counts for a 10 ft by 10 ft slab at common planning thicknesses.
Concrete guide Recommended Concrete Slab Thickness for Patios, Sheds, and DrivewaysLearn how slab thickness affects concrete volume, bag count, and planning assumptions before estimating material quantity.