🏧 Concrete Calculator
Calculate exactly how much concrete you need for slabs, patios, and footings.
Enter Dimensions
ft
ft
in
Standard slab is 4 inches.
Ready Mix Required
0
Cubic Yards
80 lb Bags Needed
0
Yields ~0.60 cu ft/bag
60 lb Bags Needed
0
Yields ~0.45 cu ft/bag
Total Volume in Cubic Feet: 0 ft³
How to Order Concrete
If your project requires more than 1.5 to 2 cubic yards of concrete, it is almost always cheaper and easier to order a Ready Mix truck to deliver it.
If your project is smaller than 1.5 yards, you can buy individual 80lb or 60lb pre-mixed bags from a hardware store and mix it yourself using a wheelbarrow or a rented electric mixer.
Never forget the 10% rule: The ground is never perfectly flat. A slab that you dug out to be 4 inches deep might be 4.5 inches deep in the middle. Always order 10% more concrete than your mathematical calculation requires.
Concrete Math & Formulas
- Find Cubic Feet: Length (ft) × Width (ft) × Depth (in feet). To convert a 4-inch depth to feet, divide by 12 (4 / 12 = 0.333 ft).
- Find Cubic Yards: Divide your total cubic feet by 27. (Since a yard is 3x3x3, there are 27 cubic feet in one cubic yard).
Frequently Asked Questions
How many 80 lb bags of concrete are in a yard? +
It takes exactly 45 bags of 80 lb concrete to make one cubic yard. (An 80 lb bag yields 0.60 cubic feet, and there are 27 cubic feet in a yard: 27 / 0.60 = 45).
How deep should my concrete slab be? +
For a standard walking patio or sidewalk, 4 inches is the standard depth. If you are pouring a driveway that will support heavy vehicles or trucks, you should pour it 6 inches deep and use reinforcing rebar or wire mesh.