Concrete Calculator
Calculate the number of bagged concrete mix needed for slabs, post holes, and footings — for any bag size.
1. Project type
2. Dimensions
feet
inches
feet
inches
Standard slab: 4" · Driveway: 6" · Walkway: 3–4"
3. Bag size, waste & price
10%
0%10%20%30%
$
How to measure your project
- 1. Slabs and pads: Measure length × width in feet. Standard thickness is 4" for patios and walkways, 6" for driveways.
- 2. Post holes: Measure or select the hole diameter and depth. A standard fence post hole is 6–8" diameter, 36" deep.
- 3. Footings: Measure the rectangular cross-section length × width × depth.
- 4. Bag size: 80 lb bags are the most efficient per bag but heaviest to carry. 60 lb bags balance size and yield. 40 lb bags are easiest to handle.
Formula: Volume (cu ft) = Area × Thickness ÷ 12. Bags = Volume × (1 + waste) ÷ bag yield, rounded up. Bag yields per Quikrete specifications. See our methodology page.