Project category
Concrete Calculators
Plan simple rectangular concrete slabs by estimating volume in cubic feet and cubic yards, then converting that volume into bag count from a bag yield.
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.
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.
Concrete How Many 80 lb Bags of Concrete for a 10x10 Slab?This example uses the 80 lb bag yield preset for a 10 ft by 10 ft slab, then lets you change thickness or bag yield.
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.
- Check whether a bagged project is becoming large enough to discuss ready-mix options.
Common inputs
- Slab length and width in feet.
- Slab thickness in inches.
- Concrete bag yield and waste factor.
FAQ
Do these calculators provide ready-mix pricing?
No. They estimate volume and material quantity only. They do not provide live prices, delivery fees, or contractor quotes.
Where should bag yield come from?
Use the yield printed on the concrete bag or supplied by the manufacturer.