Project category
Concrete Calculators
Plan a rectangular concrete slab in cubic feet, cubic yards, and bags, then optionally check mixer batches and costs from values you enter.
Tools
Concrete calculators
Open a calculator to adjust dimensions, material size, waste factor, assumptions, and optional user-entered unit price.
Worked examples
Use these scenario pages when your project is close to a common size, then edit the embedded calculator inputs.
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.
Concrete How Much Concrete for a 12x12 Slab?This example starts with a 12 ft by 12 ft slab at 4 in thick and embeds the concrete calculator so you can adjust thickness, yield, and waste. The quick-answer table below covers 4 in, 6 in, and 8 in thickness for both 60 lb and 80 lb bags.
When to use these tools
- Estimate concrete for small pads, shed slabs, walkway sections, and repair projects.
- Compare 40 lb, 60 lb, and 80 lb bag yield assumptions.
- Estimate mixer batches from the batch capacity you enter.
- Compare bagged and ready-mix material cost only when you have your own supplier values.
Common inputs
- Slab length and width in feet.
- Slab thickness in inches.
- Concrete bag yield and waste factor.
- Optional mixer capacity, bag price, ready-mix price, minimum order, and fees.
FAQ
Do these calculators provide ready-mix pricing?
They do not provide live prices or quotes. The slab calculator can total a ready-mix price, minimum order, delivery fee, and short-load fee only when you enter those values yourself.
Where should bag yield come from?
Use the yield printed on the concrete bag or supplied by the manufacturer.