Concrete Calculator
Calculate concrete volume for slabs, columns, and footings
What is the Concrete Calculator?
The concrete calculator tells you how many cubic yards, cubic feet, or cubic meters of concrete you need for a pour. Get this wrong and you're either making extra trips to the supplier or, worse, running short mid-pour. Slabs, footings, columns, and round tube forms all have slightly different volume formulas. CalciHub's calculator handles the most common shapes — rectangular slabs, circular slabs, and cylindrical columns — and adds a waste factor you can adjust.
How Does It Work?
Concrete volume is just geometry. For a rectangular slab, multiply length × width × thickness. For a cylinder (like a column or tube form), use the circle area formula times the height. The result comes out in cubic units. Since concrete is typically ordered in cubic yards, the calculator converts automatically.
Rectangular slab: V = Length × Width × Thickness Cylindrical column: V = π × r² × Height 1 cubic yard = 27 cubic feet
• V = volume of concrete needed
• Length, Width, Thickness = slab dimensions
• r = radius of the cylinder or column
• Height = height or depth of the pour
• π ≈ 3.14159
How to Use CalciHub's Concrete Calculator
1. Select your pour shape: rectangular slab, circular slab, or column.
2. Enter the dimensions in your preferred units (feet, inches, or meters).
3. Adjust the waste percentage if needed — 10% is a common allowance.
4. Click Calculate — the result shows volume in cubic yards, cubic feet, and bags of premix if applicable.
Tip: Always order slightly more than your calculated amount — a 5–10% overage is standard practice to account for spillage, settling, and uneven ground.
A Quick Example
A 12 ft × 20 ft driveway slab, 4 inches thick. Convert 4 inches to feet: 4/12 = 0.333 ft. Volume = 12 × 20 × 0.333 = 80 cubic feet. Convert to cubic yards: 80 / 27 ≈ 2.96 cubic yards. With a 10% waste factor, you'd order approximately 3.26 cubic yards — round up to 3.5 when placing the order. Enter these dimensions into CalciHub and it handles the unit conversion and the waste calculation in one step.
A 4-inch slab is standard for driveways; stepping up to 6 inches increases your concrete needs by 50%, which matters when you're pricing the job.
Frequently Asked Questions
For a basic walkway or patio, 4 inches is typical. Driveways that see car traffic usually need 4 to 6 inches. Heavy loads like trucks or equipment require 6 inches or more. Structural applications may call for much thicker pours.