Concrete Calculator interactive tool
* Note: This is a dimensional estimate. Consider adding 5-10% for spills, uneven subgrades, and waste, then confirm the order with your supplier.
What Is Concrete?
A concrete materials calculator estimates the volume of concrete required for slabs, patios, footings, and other projects. It converts the dimensions you enter into cubic feet, cubic yards, and approximate premixed bag counts.
Understanding Cubic Yards
In the construction industry, bulk concrete is ordered and delivered by the cubic yard.
- 1 cubic yard equals 27 cubic feet (an area 3 feet wide, 3 feet long, and 3 feet deep).
- A standard ready-mix concrete truck holds between 8 and 10 cubic yards of concrete.
Bags vs. Bulk Delivery: How Many Bags of Concrete Do I Need?
For smaller projects, it is more economical to buy pre-mixed bags of concrete at a home improvement store. Our tool automatically converts your required volume into the number of standard bags you need to buy:
- It takes roughly 60 bags of 60 lb concrete to make one cubic yard.
- It takes roughly 45 bags of 80 lb concrete to make one cubic yard.
Planning note: A 5% to 10% allowance may help cover spills, uneven subgrades, and form variation. Confirm the quantity and mix requirements with a supplier or contractor, especially for structural work.
How To Use the Concrete Calculator
- Choose the shape of your concrete pour (e.g., rectangular slab, circular column) from the dropdown.
- Enter the dimensions of your project (length, width, and depth/thickness) in the respective fields.
- Review the estimated volume in cubic feet and cubic yards.
- Review the breakdown of how many pre-mixed bags (60lb or 80lb) you would need to buy for your project.
- Consider adding a 5-10% waste factor for spills or uneven forms.
Cubic yards and bags of concrete
Use this concrete calculator for slabs, footings, and columns when you need volume in cubic feet or cubic yards and an estimate of 60- or 80-pound premixed bags. Add a practical waste allowance and confirm the yield on the product label.
Need the formula or convention behind this result? Read the calculator methods and assumptions.