Free Concrete Calculator
Figure out how many cubic yards or bags of concrete you need for your project. Whether you're pouring a slab, footing, or stairs, our calculator provides accurate estimates for volume, weight, and bag quantities to help you order the right amount.
Project Details
Adjust Dimensions
Pre-mixed
Calculate Concrete
Click to calculate volume, weight, and bag requirements
Why Use a Concrete Calculator?
Ordering the right amount of concrete is crucial. If you order too little concrete, you might face delays, extra delivery charges, or weak spots in your pour. Ordering too much concrete wastes money and materials.
Using a concrete calculator lets you:
- Calculate concrete volume in cubic yards or cubic feet
- Estimate how many 80 lb or 60 lb concrete bags you'll need
- Avoid costly overages or shortages
- Plan your budget more accurately
Common Uses
Our handy concrete calculator helps you quickly estimate how much concrete you need for:
- Driveways
- Sidewalks
- Patios
- Footings & foundations
- Columns
How To Calculate Concrete Volume
The basic formula for concrete volume is simple:
For a rectangular slab:
Volume = (Length × Width × Thickness) ÷ 12
- Measure length and width in feet
- Measure thickness in inches
- Divide by 12 to convert thickness to feet
- Multiply to find cubic feet
- Divide by 27 to get cubic yards
Our calculator does the math for you in seconds.
Simply choose your project shape and adjust your measurements using the sliders, buttons, or manual input. Select your preferred units and the tool does the math with automatic conversions.
How Many Bags of Concrete Do You Need?
If you're working on smaller projects, you might use pre-mixed concrete bags. An 80 lb bag covers approximately 0.6 cubic feet.
To find the number of bags:
Bags Needed = Total Cubic Feet ÷ 0.6
Our calculator automatically shows you how many 60 lb or 80 lb bags you'll need for your project.
Frequently Searched Questions About Concrete Calculations:
- How much concrete do I need for a slab?
- How to calculate concrete for a driveway?
- How many bags of concrete for a patio?
- Do I need to order extra concrete?
- How much concrete do I really need?
- How to convert cubic feet of concrete to cubic yards?
Order a Little Extra
It's always smart to order about 10% more concrete than you calculate. This covers spillage, uneven ground, and slight measurement errors. It's better to have extra than come up short during your pour!