How do I calculate how much concrete I need?

To calculate concrete needed, multiply length × width × depth to get volume in cubic feet, then divide by 27 to convert to cubic yards. For example, a 10ft × 10ft slab that's 4 inches thick: (10 × 10 × 0.33) ÷ 27 = 1.22 cubic yards. Our calculator handles all conversions automatically.

How many bags of concrete do I need?

The number of bags depends on the bag size: 40 lb bags yield about 0.011 cubic yards, 60 lb bags yield about 0.017 cubic yards, and 80 lb bags yield about 0.022 cubic yards. Our calculator tells you exactly how many bags of each size you'll need for your project.

How thick should a concrete slab be?

Standard residential slabs (patios, walkways) are typically 4 inches thick. Driveways should be at least 4-6 inches, with 6 inches recommended for heavy vehicles. Garage floors are usually 4-6 inches. Commercial applications may require 6-8 inches or more depending on load requirements.

Should I order extra concrete?

Yes, always order 5-10% extra concrete to account for spillage, uneven ground, and settling. Our calculator includes a waste factor option to help you determine the right amount. Running short during a pour can compromise the structural integrity of your project.

Concrete Calculator | Galick Tools

Concrete Calculator

Calculate the amount of concrete needed for your project. Supports slabs, columns, and circular footings.

Slab / Square

Column / Footing

Tube / Cylinder

Length

Width

Depth / Thickness

Quantity

Waste Factor

Recommended: 10% for waste/spillage

Concrete Coverage Guide

Common depths and their typical uses:

4 inches: Sidewalks, patios, most residential slabs
6 inches: Driveways, garage floors, heavier traffic areas
8+ inches: Commercial applications, heavy equipment pads

Formulas Used

Slab: Volume = Length × Width × Depth

Cylinder: Volume = π × (Diameter/2)^2 × Height

Cubic Yards = Cubic Feet ÷ 27

Concrete Calculator

Concrete Needed

Pre-Mixed Bags Needed

Concrete Coverage Guide

Formulas Used