Concrete Slab Cost & Volume Calculator
4 inches (Standard)
5 inches
6 inches (Heavy Duty)
8 inches
12 inches
Total Volume
0
Cubic Yards
Est. Material Cost
$0.00
Based on yard price
Total Project Cost
$0.00
Materials + Labor
Premix Bags (80lb)
0
If not using truck delivery
Premix Bags (60lb)
0
Alternative option
Total Weight
0
Pounds (Approx)
How to Calculate Concrete Costs for Your Slab
Planning a driveway, patio, or shed foundation requires accurate material estimation. Ordering too little concrete can lead to cold joints and structural weaknesses, while ordering too much wastes money. This Concrete Slab Cost Calculator helps you determine exactly how many cubic yards of concrete you need, factoring in standard waste margins, and estimates your financial investment.
The Concrete Calculation Formula
To calculate the volume of concrete needed for a slab, you must calculate the volume in cubic feet and then convert it to cubic yards, which is the standard unit for pricing and delivery in the US.
Formula:
(Length (ft) × Width (ft) × Thickness (ft)) / 27 = Cubic Yards
(Length (ft) × Width (ft) × Thickness (ft)) / 27 = Cubic Yards
Since slab thickness is usually measured in inches, you must first divide the inches by 12 to get the thickness in feet. For example, a 4-inch slab is 0.33 feet thick.
Standard Slab Thickness Guidelines
- 4 Inches: The industry standard for residential sidewalks, patios, and standard driveways supporting passenger vehicles.
- 5-6 Inches: Recommended for driveways that host heavier vehicles (RVs, large trucks) or for hot tub pads to prevent cracking under load.
- 8+ Inches: Typically reserved for commercial loading docks or heavy machinery foundations.
Understanding the Waste Factor
Concrete projects rarely go perfectly according to plan. Uneven subgrades, spillage during pouring, and form-bending can increase the amount of material required. Our calculator includes a default 10% waste margin (which you can adjust). It is highly recommended to include this buffer to avoid running short during the pour.
Bagged Concrete vs. Ready Mix Truck
When should you buy bags, and when should you call a truck?
- Bagged Concrete (60lb or 80lb): Ideal for small projects requiring less than 1 cubic yard (approx. 45-60 bags). It is labor-intensive to mix.
- Ready Mix (Truck Delivery): Best for any project over 1 yard. While there may be a "short load" fee for small orders, the quality of the mix is consistent, and it saves immense physical labor.