Length (ft) Enter the length of the concrete area in feet (e.g., 20)

Width (ft) Enter the width of the concrete area in feet (e.g., 10)

Thickness (in) Enter the thickness or depth of concrete in inches (e.g., 4 for a standard slab)

Quick Examples:

Standard Patio Slab Small Walkway

Calculate Clear

This calculator provides estimates only. Actual concrete requirements may vary based on site conditions, waste, spillage, and subgrade variations. Consult a concrete professional for accurate material ordering and project planning.

Use this free online Concrete Calculator to calculate your concrete volume. Simply enter your length, width, and thickness to instantly get results in cubic yards and cubic feet. This estimate helps you plan material purchases for slabs, patios, walkways, and other rectangular concrete projects.

How Concrete Volume Is Calculated

Concrete volume is calculated by finding the three-dimensional space the concrete will fill. The calculator multiplies the length, width, and thickness together. Since thickness is measured in inches but length and width are in feet, the thickness must first be converted to feet by dividing by 12. The result gives volume in cubic feet, which is then divided by 27 to convert to cubic yards, the standard unit for ordering concrete.

This formula works best for rectangular slabs with uniform thickness. For irregular shapes, break the area into smaller rectangles and calculate each separately.

What Your Concrete Volume Result Means

Your result shows how much concrete you need to fill the specified area. Concrete is typically ordered in cubic yards from ready-mix suppliers. A standard residential patio of 10 by 12 feet with 4-inch thickness requires about 1.48 cubic yards. A larger driveway of 20 by 20 feet with 6-inch thickness needs approximately 7.41 cubic yards. Most suppliers have a minimum order, often 1 cubic yard, and charge for partial loads.

When ordering concrete, consider adding 5 to 10 percent extra to account for spillage, uneven subgrade, and slight variations in form dimensions.

Accuracy, Limitations & Common Mistakes of the Concrete Calculator

How Accurate Is the Concrete Calculator?

The calculator provides accurate volume estimates for rectangular slabs with uniform thickness. The math is precise when dimensions are measured correctly. However, real-world factors like ground unevenness, form board placement, and finishing techniques can affect the actual amount needed. Professional contractors typically add a waste factor of 5 to 10 percent to calculated volumes.

Limitations of the Concrete Calculator

This calculator assumes a perfect rectangular shape with consistent thickness throughout. It does not account for irregular shapes, slopes, stepped foundations, or varying thicknesses. The calculator also excludes waste factors, spillage, over-excavation, and subgrade irregularities. For complex projects like curved walkways, stepped footings, or reinforced structures, consult a concrete professional for precise estimates.

Common Mistakes to Avoid

• Forgetting to add a waste factor: Order 5 to 10 percent more concrete than calculated to account for spillage and uneven surfaces.
• Mixing up thickness units: Remember that thickness is entered in inches, while length and width are in feet.
• Measuring incorrectly: Double-check all measurements and ensure the area is truly rectangular before calculating.

Frequently Asked Questions

Who is this Concrete Calculator for?

This calculator is designed for homeowners, DIY enthusiasts, and contractors who need quick volume estimates for rectangular concrete projects. It works well for planning patios, walkways, driveways, shed floors, and similar flatwork. Professional engineers may need more detailed calculations for structural applications.

How do I order the right amount of concrete?

Calculate your volume using this tool, then add 5 to 10 percent for waste. Contact your local ready-mix supplier and provide the total cubic yards needed. They can help confirm your order and suggest the appropriate concrete mix for your project type and climate conditions.

What if my project has an irregular shape?

Break the area into smaller rectangles and calculate each section separately. Add all the volumes together for a total estimate. For curved areas, use a series of small rectangles to approximate the shape, or consult a professional for more precise measurements.

How thick should my concrete slab be?

Thickness depends on the intended use. Standard sidewalks and patios typically use 4 inches. Driveways for standard vehicles use 4 to 6 inches. Heavy vehicle areas or foundations may require 6 inches or more. Check local building codes for minimum requirements in your area.

Is the Concrete Calculator free to use?

Yes, this calculator is completely free with no sign-up required. You can use it on any device as many times as needed for your projects.