How to Calculate Amount of Concrete Needed for Slab

Pouring a concrete slab can be done by the do-it-yourself homeowner.

Pouring a concrete slab is a task that do-it-yourself homeowners can accomplish. Because of the "one-shot" nature of installing concrete, it is important to purchase or order enough to complete the job. Concrete is ordered in terms of "yards of concrete," which can be figured once you know the total square footage of the proposed slab.

Things You'll Need

• Measuring tape
• Calculator

Instructions

1. Measure the area where the concrete slab will be poured to determine its length and width. If it is irregularly shaped, take the measurements at the widest width and the longest length.

2. Using the measurements arrived at in Step 1, multiply the width times the length to arrive at the total square footage of the planned concrete slab.

3. Decide or determine the depth to which the slab will be poured and leveled.

4. Divide the depth of your proposed concrete slab into the number 320.

5. Divide the total square feet of your proposed concrete slab by the figure you arrived at in Step 4. The resulting figure will be the amount of concrete needed for your proposed slab, expressed in terms of "yards of concrete," the standard measure in the industry.

Tips & Warnings

• If the area is severely irregularly shaped, break the area up into a series of rectangles or squares. Measure these areas, then figure their square feet according to Step 2. Next, add the total square feet of all of the component rectangles and/or squares, to arrive at the total square footage of the proposed slab. Use that total as part of your calculations in Step 5.

• An acceptable estimate of concrete needed is to divide the total square footage into the number 320. This works on all geometric shapes, even circles, as long as you know the square footage of the geometric shape.

References

• Sandee's Soil & Rock: To Estimate the Amount of Concrete Needed

Resources

• Westroc Inc.: Figuring Concrete Quantity