Concrete Calculator
Calculate how many bags of concrete you need for slabs, footings, posts, and more.
Concrete Calculator
Calculate how many bags of concrete you need
Formula
Volume = Length × Width × (Thickness ÷ 12)Includes 10% extra for waste
How to Use This Calculator
- 1
Enter dimensions
Enter the length, width, and thickness of your concrete project.
- 2
Review volume
See the total volume in cubic feet and cubic yards.
- 3
Choose bag size
The calculator shows bags needed for 40, 60, and 80 lb options.
Frequently Asked Questions
How thick should a concrete slab be?
For patios and walkways, 4 inches is standard. Driveways typically need 5-6 inches. Always check local building codes.
How many bags of concrete in a cubic yard?
Approximately 45 bags of 80 lb concrete, 60 bags of 60 lb, or 90 bags of 40 lb make one cubic yard.
Should I add extra concrete?
Yes, this calculator includes 10% extra for waste. For uneven ground, consider adding more.