How can I calculate the square footage of my house from the outside? Serious answers only please. Thank you!

Question

How can I calculate the square footage of my house from the outside? Serious answers only please. Thank you!

Answer 1

For real estate comparison purposes, the heated and cooled area of the dwelling is always calculated from exterior measurements.  The exceptions are condos, HPRs, and other structures with party (common) walls.

Depending on the design of the house and the purpose for which you need to know the area, other complications can arise, including treatment of below grade areas, finished attic space with low ceilings, contemporary styles with partial floor levels, interior courtyards, and partially finished spaces.

Your county tax assessor will likely have the square footage that is used to calculate your real estate taxes.  These records are online in many areas.  Assessor measurements can vary greatly in accuracy from county to county, so don't base any important decisions on them.

If the house is of a simple design and all above grade, simply measure the outside walls and use the appropriate area formulas to find the square footage.  If it's a little more elaborate, sketch it while you're measuring and then break the areas down into squares, rectangles, and triangles, calculate their areas and then add them together.  For attached garages, the finished wall inside the garage is the outside wall of the house.

If the house is too complicated and you need an accurate figure for whatever reason, you may require the assistance of a real estate agent with experience measuring homes (not all do) or an appraiser, for whom it's an everyday part of the job.

Answer 2

Not very accurately.

The "square footage" of a house generally includes only the actual livable areas of the house -- the square footage of each room added together, leaving out "blank" spots like halls, stairways, etc. If you just measure the outside of your house and calculate the square footage that way, you will be overestimating and your numbers will be misleadingly large.