Concrete Slab Calculator

Slab concrete volume is the slab surface area multiplied by its thickness. Enter length × width × thickness, or enter the slab area and thickness directly — both routes produce the same volume, shown in cubic yards, cubic feet and cubic meters, with your waste allowance applied separately to the recommended order.

1. 1Choose Length × Width or Enter Area.
2. 2Enter the slab measurements and select units.
3. 3Enter the slab thickness, or use a thickness shortcut.
4. 4Select a waste allowance and the number of identical slabs.
5. 5Optionally enter your local concrete price, then select Calculate.

Volume = Length × Width × Thickness. Every measurement is normalized before multiplying, so you can mix feet, inches, meters and centimeters. In Enter Area mode the same result comes from Area × Thickness.

Concrete volume changes significantly with thickness. The same surface area at 6 inches thick requires 50% more concrete than at 4 inches thick, because 6 ÷ 4 = 1.5. A small thickness change on a large slab can therefore change your order by a full load.

The appropriate slab thickness depends on the project, loads, soil and subgrade conditions, reinforcement, local codes and engineering requirements. Use the thickness specified for your project.

• Verify the slab dimensions in several places — slabs are rarely perfectly square.
• Confirm the thickness specified for your project before ordering.
• Account for uneven excavation and subgrade with a suitable waste allowance.
• Confirm the yield printed on the bag if you plan to mix bagged concrete.
• Check supplier minimum delivery quantities if you are considering ready-mix.