Use this concrete calculator to turn finished pour dimensions into net volume, an order quantity with a visible overage, and whole premix bag counts. The reverse option shows how much area the bags already on hand can cover at a stated thickness.
How to calculate concrete for a pour
Select the pour shape, enter finished dimensions, and keep the visible quantity and extra-concrete fields aligned with the work being ordered.
Worked example
- A 10 × 10 slab at 4 thick contains 33.33 , or 1.23 , before extra concrete.
- With the visible 10% allowance, the order quantity is 1.36 and the 80 bag estimate is 62 bags at the published 0.60 yield.
Concrete bag yields
QUIKRETE publishes yields of 0.30 for a 40 bag, 0.45 for a 60 bag, and 0.60 for an 80 bag. The calculator divides adjusted volume by the selected yield and rounds up to a whole bag.
Bags or ready-mix?
Use cubic yards when discussing a ready-mix delivery and whole-bag counts when buying the selected premix product. Net volume and order volume stay separate so the visible extra-concrete percentage never disappears into the dimensions.
Frequently asked questions
How do I calculate cubic yards of concrete?
Convert all dimensions to feet, calculate the shape's cubic feet, and divide by 27. For a rectangular slab, multiply length by width by thickness in feet before dividing by 27.
How many bags of concrete do I need?
Divide the concrete volume after your chosen overage by the published yield of one bag, then round up. This calculator uses 0.30 for 40 , 0.45 for 60 , and 0.60 for 80 QUIKRETE Concrete Mix bags.
How much extra concrete should I order?
Enter the allowance that matches the job and supplier guidance. The calculator keeps net volume and order volume separate so the added percentage stays visible instead of being hidden in the dimensions.