To determine how many bags of concrete you need for a 10x12 slab, you need to consider the thickness of the slab. Here’s a step-by-step guide to calculate it:

1. Determine the Volume of Concrete Needed

Concrete volume is calculated in cubic feet or cubic yards.

2. Convert to Cubic Yards

Concrete is often measured in cubic yards for large projects.

3. Determine Bags of Concrete Needed

Concrete is sold in bags of various sizes. Common sizes are 40, 50, 60, and 80 pounds. Each size yields a different amount of concrete.

Here’s how much volume each bag size covers:

• 40-pound bag: ~0.30 cubic feet
• 50-pound bag: ~0.38 cubic feet
• 60-pound bag: ~0.45 cubic feet
• 80-pound bag: ~0.60 cubic feet

Calculate the number of bags required for each size:

Summary

For a 10x12 slab with a thickness of 4 inches, you need approximately:

• 132 bags of 40-pound concrete
• 104 bags of 50-pound concrete
• 88 bags of 60-pound concrete
• 66 bags of 80-pound concrete

Choose the bag size that is most convenient for your project and budget.