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How to Calculate Square Footage

Tape measure on floor.

If you have decided to upgrade your flooring, and feel overwhelmed about where to start, start here. Knowing how to calculate square footage is an important skill to learn before replacing any flooring. Measuring accurately will ensure you order the right amount of material – without running out or having too much left over. Learning this simple square footage formula is the first step towards beautiful new flooring. This method can also be used for calculating paint, tiles, grass seed and more.

Skill Level: Beginner
  1. Step 1 Measure the Area You Want to Calculate

    Man measuring floor.

    The first step is to measure the length and width of the surface you need to calculate. To find length, locate the longest side of the area to be measured. Fix a tape measure to one end of the length and extend it to the other end. Record the measurement. To find the width, locate the shortest side of the area to be measured. Repeat the process and then record that measurement.

  2. Step 2 Calculate the Square Footage of the Area

    Person calculating on paper.

    Once you have your measurements, multiply the length in feet by the width in feet. This yields a number called the area, which is expressed in square feet (or square inches if you are calculating a much smaller space).

    L x W = A

    For example, if you are buying flooring for a room that is 12 feet long and 10 feet wide, multiply the two dimensions:

    12 ft x 10 ft = 120 sq. ft    

    If the space you’re measuring isn’t square or rectangular, you’ll need to divide it into separate areas to measure (several rectangles that make up a large room, for example). Draw it out as a floor plan and label each area A, B, C, etc.

    First calculate the square footage of each area. Then add the calculations together to get the total square footage.

    For example, if you’re trying to buy flooring for a T-shaped room, the shape is formed as a centre rectangle and two smaller rectangles or squares.

    Find the length and width of each section, then calculate each square footage:

    A: 8 ft. x 12 ft. = 96 sq. ft.

    B: 4 ft. x 2 ft. = 8 sq. ft.

    C: 4 ft. x 2 ft. = 8 sq. ft.

    Then add the three values together to get the total square footage you’ll need:

    96 + 8 + 8 = 112 sq. ft.

    You’ll need about 112 sq. ft. of flooring, plus about 10% extra to account for waste (see below).

  3. Step 3 Account for Waste in Your Project

    Home Depot employee helping a customer.

    Add about 5-10% extra materials to account for waste from your flooring project. This doesn’t mean that you’re planning to waste the flooring, but mistakes can happen. If you accidentally break tiles and you have only the exact amount you needed, you may find yourself scrambling to order more materials. Or worse, in the case of some materials, you may find yourself unable to get an exact colour match with the first batch you ordered.

    For this reason, flooring professionals recommend ordering 5-10% more materials than the area you’ve calculated. Materials like tile can often be returned if the boxes haven’t been opened or used, so that you can recover a little of your extra cost once the project is complete. However, you may find it helpful to store the extra materials, in case you need to replace tiles or wood planks down the road.

    Though learning how to calculate square footage is not difficult, there are shortcuts to the process. You can find online square foot calculators that help you determine your measurements and estimate the amount of various materials you’ll need, for everything from flooring to paint. No matter how you go about it, remember to accurately measure your space as the first step in replacing flooring. Knowing how much flooring you’ll need will give you an idea of how much to budget for the project and how long it will take.

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