How Many Concrete Bags Do I Need for a 10x10 Slab?

Quick Answer

A 10x10 slab at 4 inches thick needs about 1.23 cubic yards before waste, or about 1.36 cubic yards with 10% waste. That is roughly 82 sixty-pound bags or 61 eighty-pound bags.

Use the [Concrete Calculator](/concrete-calculator) to adjust the dimensions, waste factor, product coverage, and unit price for your exact project.

Formula

``

Cubic yards = length x width x thickness / 27

``

Example Estimate

1. Convert 4 inches to 0.333 feet.

2. Multiply 10 x 10 x 0.333 = 33.3 cubic feet.

3. Divide by 27 = 1.23 cubic yards.

4. Add 10% waste = 1.36 cubic yards.

Reference Table

| Thickness | Cubic yards with 10% waste | 60 lb bags | 80 lb bags |

|---|---:|---:|---:|

| 4 inches | 1.36 | 82 | 61 |

| 5 inches | 1.70 | 102 | 77 |

| 6 inches | 2.04 | 123 | 92 |

Practical Tips

- Use ready-mix for larger slabs if mixing dozens of bags is impractical.

- Use 10% waste for clean rectangular slabs.

- Use 15% waste for uneven ground or irregular forms.

When to Round Up

Round up when the project has cuts, corners, fragile materials, uneven surfaces, delivery minimums, or any chance that matching the same product later will be difficult.

Next Step

Open the [Concrete Calculator](/concrete-calculator), enter your exact numbers, and save the estimate before buying materials.