Concrete Calculator Square Feet

This concrete calculator helps you determine the volume of concrete needed for a project in square feet. Whether you're building a driveway, patio, or foundation, knowing the exact amount of concrete required saves time and money.

How to Use This Calculator

Using our concrete calculator is simple:

Enter the length of your project area in feet
Enter the width of your project area in feet
Select the concrete thickness in inches
Click "Calculate" to get your results

The calculator will provide you with the total volume of concrete needed in cubic feet and cubic yards, as well as the number of concrete bags required based on standard bag sizes.

Formula Explained

The concrete volume is calculated using the following formula:

Volume (cubic feet) = Length (feet) × Width (feet) × Thickness (feet)

Where thickness is converted from inches to feet by dividing by 12. The calculator also converts cubic feet to cubic yards by dividing by 27.

For bag count estimation, we use standard 80-pound bags of concrete, assuming each bag covers approximately 0.1 cubic yards.

Worked Examples

Example 1: Driveway

For a 20-foot long, 10-foot wide driveway with 4-inch concrete:

Volume = 20 × 10 × (4/12) = 6.667 cubic feet

Cubic yards = 6.667 / 27 ≈ 0.247 cubic yards

Bags needed = 0.247 / 0.1 ≈ 2.5 bags (round up to 3)

Example 2: Patio

For a 12-foot square patio with 3-inch concrete:

Volume = 12 × 12 × (3/12) = 3.6 cubic feet

Cubic yards = 3.6 / 27 ≈ 0.133 cubic yards

Bags needed = 0.133 / 0.1 ≈ 1.3 bags (round up to 2)

Comparison Table

Project	Dimensions	Thickness	Volume (cubic ft)	Bags Needed
Small Patio	6' × 6'	2.5"	2.29	2
Medium Driveway	15' × 10'	4"	12.5	5
Large Foundation	20' × 15'	6"	30	11

Frequently Asked Questions

How accurate is this calculator?

This calculator provides an estimate based on standard formulas. Actual concrete requirements may vary slightly due to material waste and project-specific conditions.

What thickness should I use for my concrete?

Standard thicknesses are 2-4 inches for driveways and patios, and 4-6 inches for foundations. Consult with a professional for your specific project needs.

How do I convert cubic feet to cubic yards?

Divide the volume in cubic feet by 27 to get cubic yards. For example, 27 cubic feet equals 1 cubic yard.