Calculating Floor Area In 5 Steps Calculating Floor Area In 5 Steps

It's easy to calculate the area of your floor, even if the room is oddly shaped. Just break it down into these 5 simple steps.

  1. Assuming that your room has at least one long straight wall that connects with two side walls, measure this long wall and convert the measurement to feet (odd inches should be expressed as decimals).
  2. Assuming that your room has at least one short straight wall that connects with two long walls, measure this short wall and convert the measurement in the same way.
  3. Multiply one measurement by the other. This is the area of the room if it were square, expressed in square feet.
  4. For each bump-out in the room, measure the length of each side of it, convert to feet, multiply one by the other, and subtract the result from the "square room" measurement.
  5. For each recess in the room, measure the length of each side of it, convert to feet, multiply one by the other, and add the result to the "square room" measurement.

Here's an example:  Your room is 10' x 10' square. It has a 1' x 1' bump-out for ductwork and a 3' x 3' ell at the doorway.

  • 10 x 10 = 100 sq. ft.
  • 1 x 1 = 1 sq. ft."
  • 3 x 3 = 9 sq. ft.
  • (100 – 1) + 9 = 108 sq. ft.

Remember that the various materials you may use to cover the floor will have different demands, so your base measurement is a launching point for figuring out your actual material needs.

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