How Do You Figure Square Footage?

by Team HomeServe Top Tips and Lists  

I wouldn't say I'm mathematically challenged - but I will admit that I haven't thought about formulas since I took statistics during my first year of college. Needless to say, calculating the square footage of my house seemed like quite the challenge. While it did take up a decent part of my Sunday afternoon, it actually wasn't as difficult as I expected it to be. No matter your mathematical abilities, I promise you can do it too.

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Here's how to determine the square footage of your house:

Conduct the calculations

Let's start small, calculating the square footage of a basic room. Simply use a measuring tape or laser measure to determine the length and width of the space in feet. Multiply the numbers together and you have the room's square footage.

Example: 20 feet x 10 feet = 200 square feet.

To calculate the square footage of an entire home, the basic formula is to measure the area of every room and add them all together for the final number. Of course, not every room is a perfect square, but do your best to break up larger spaces into manageable boxes that are easy to measure.

U.S. News and World Report offers formulas for more complicated shapes:

  • Triangular areas: Multiple the base and height of a right triangle and divide by two. You might need to break the area into two right triangles to get the right measurement.
  • Round rooms: Calculate the circle area by measuring the radius. Take the square of the radius and multiply it by 5.

Pro tip: It helps to sketch out a simple floor plan of your home, so you can write down the square footage of each area as you go along.

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Zillow also notes that you should leave out the garage and basement, as most standards do not include those areas in overall square footage. Attic spaces also won't count, unless they're deemed habitable and have at least seven feet of clearance. While you have the measuring tape out, you may still want to measure the square footage of these individual spaces to have for your records. It can also be helpful when selling your home, as you can list a house as a 3,300 square foot home with 1,000 square feet of unfinished basement and 700 feet of garage space.

Leave room for discrepancies

Keep in mind that these square footage calculations are only estimates, so don't worry about getting the perfect measurements. SFGate HomeGuides suggests rounding each length and width measurement to the nearest 0.5 foot and going with the nearest square foot for the overall number.

It's also very likely that there will be discrepancies between your calculations and those completed by a real estate agent, builder, architect or other source, according to As such, many official listing services will require homeowners to list square footage calculated by a specific source or professional.

Understand the importance of square footage

For real estate agents and mortgage lenders, square footage calculations are par for the course. But why does the average homeowner need to know all these length and width measurements? Of course, the calculation is important for understanding how much home you can afford to purchase as well as determining the value of your current home when it's time to sell.

Even if you don't have plans to move in the near future, knowing the square footage of your house will come in handy in situations, such as:

  • Calculating tax payments.
  • Determining the amount of materials needed when making home improvements, such as installing new flooring or upgrading roofing shingles.
  • Purchasing appropriately sized heating and cooling units.
  • Installing energy-efficient upgrades, such as windows or solar panels.

Being prepared for home repairs before they arise is always a good strategy. See how plans from HomeServe can help with the costs of covered repairs.

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