Concrete Slab & Patio Cost Calculator
Estimated Project Materials & Costs
Total Slab Area:
0 sq. ft.
Exact Volume Needed:
0 cu. yards
Order Amount (w/ Waste):
0 cu. yards
80lb Premix Bags (for DIY):
0 bags
Estimated Concrete Cost:
$0.00
Estimated Labor:
$0.00
Total Project Estimate:
$0.00
How to Calculate Concrete Costs for Your Project
Planning a new driveway, patio, or shed foundation requires precise calculations to ensure you order enough material without overspending. Concrete is typically sold by the cubic yard, and getting the math right is the first step in a successful project.
The Concrete Calculation Formula
To determine how much concrete you need, you must calculate the volume of the space in cubic feet and convert it to cubic yards. The formula used by our calculator is:
- Step 1: Calculate Area (Length × Width)
- Step 2: Convert Thickness to feet (Inches ÷ 12)
- Step 3: Multiply Area × Thickness (in feet) to get Cubic Feet
- Step 4: Divide Cubic Feet by 27 to get Cubic Yards
Standard Thickness for Slabs
Choosing the right thickness depends on how the slab will be used:
- 4 Inches: Standard for residential patios, sidewalks, and garage floors for passenger cars.
- 6 Inches: Recommended for heavy-duty driveways (trucks/RVs) or hot tub pads.
- 5-6 Inches: Often used for shed foundations or floating slabs.
Why Include a Waste Factor?
Professional contractors always include a "waste factor" or safety margin, typically between 5% and 10%. This accounts for spillage, uneven subgrades (ground that isn't perfectly flat), and form settling. Running out of concrete mid-pour can be a disaster, creating a "cold joint" that weakens the structure, so it is always safer to order slightly more than the exact mathematical volume.
DIY vs. Ready-Mix Delivery
For small projects (less than 1 cubic yard), buying 60lb or 80lb premix bags from a hardware store is often cost-effective. However, for larger slabs like driveways, ordering "Ready-Mix" concrete from a truck is standard. Our calculator provides estimates for both cubic yardage (for trucks) and bag count (for DIY mixing).