How Much Concrete Do You Need for Your Driveway?
A properly calculated concrete order saves time, money, and stress. Our calculator simplifies the process. Just enter the dimensions of your planned slab, and it will handle the math, giving you the volume in cubic yards—the standard unit for ordering ready-mix concrete in the US and Canada.
Concrete Calculator
Use the form below to calculate the required volume for a rectangular slab. Enter your measurements in feet and inches.
📖 How to Calculate Concrete Volume (Engineering Formula)
For US-based construction projects, concrete is typically ordered by volume in Cubic Yards (yd³). If you are mixing it yourself using pre-packaged bags (Quikrete or Sakrete), you need to know the bag count based on weight (lbs).
The Basic Formula
To calculate the concrete needed for a slab, use the following equation:
Volume (yd³) = Volume (ft³) / 27
Note: There are 27 cubic feet in 1 cubic yard.
Common Questions & Conversions
How many 80lb bags of concrete are in a yard?
One cubic yard of concrete weighs approximately 4,000 lbs (cured).
- 80lb bags: You need approx. 45 bags to make 1 cubic yard.
- 60lb bags: You need approx. 60 bags to make 1 cubic yard.
Jobkithub Tip: Always round up. Our calculator automatically calculates this based on standard yield.
Why add a Waste Margin?
Professional contractors always add a 5% to 10% safety margin (waste factor) to their order. This accounts for:
- Spillage during the pour.
- Uneven sub-grade (ground) depth.
- Settling of forms.
The calculator on this page includes an optional 10% buffer in the results to ensure you don’t run out mid-pour.
Standard Slab Thicknesses
- 4 Inches: Standard for residential sidewalks, patios, and garage floors (light vehicles).
- 5-6 Inches: Recommended for heavy driveways (trucks/SUVs) or hot tub pads.
Final Tips Before You Order
- Call Local Suppliers: Concrete prices per cubic yard vary by region, mix strength, and delivery fees.
- Prepare the Site: Ensure the base (usually compacted gravel) is properly prepared before the truck arrives.
- Consider Accessibility: Can the ready-mix truck reach the pour site easily? Inform the supplier of any obstacles.
Using our concrete calculator takes the guesswork out of planning your driveway project. Get your estimate, contact your local ready-mix company, and move forward with confidence.