Question: How can I estimate how many bags or buckets of product I will need for a particular job?

Answer: You might assume that ordering the right amount of material would be a no-brainer as long as you accurately measure the size of your project. In reality though, the math isn’t quite that simple. To accurately measure material quantities, you must compensate for factors such as spillage and waste and the thickness of your placement. Here are some simple formulas you can use to ensure that you order enough material and never have to suffer the gut-wrenching feeling of running short during an installation.

Measuring project size

The most common method of estimating materials is based on the square footage of the area to be installed. This is easily determined by multiplying the length of the slab by the width. For example, a project measuring 30 x 30 feet would equal 900 square feet.

For projects with areas that aren’t perfect squares or rectangles, the best strategy is to break down the areas into rectangular sections to determine the square footage. Where you are left with irregular or pie-shaped sections, find the halfway point and average in both directions. You can obtain surprisingly accurate estimates using this approach, especially for large areas.

Coverage rates for overlay materials are based on the installed thickness. So if the technical data sheet indicates that a bag of self-leveling overlay placed at a thickness of 1/4 inch will cover about 25 square feet of surface area, you would take the square footage of your project and divide it by 25 to calculate the number of bags or units needed:

900 square feet ÷ 25 square feet/bag = 36 bags of material