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How do Appraisers Measure a Home?

How do you know the size of your home? The tax records have a measurement, sometimes an MLS listing has a measurement and then an appraiser measures your home and there is a different measurement! How can this be? We will try to explain how an appraiser measures your home and why there is sometimes discrepancies in the measurements.

Appraiser Measurements:

Appraisers will measure the exterior of your home first. Many appraisers use either a tape measure or a laser measure. We actually use both as the laser measure works well when the exterior a home has large brush that makes it difficult to use.

It is of note that garages and basements will not be counted as part of the living area calculation although appraiser will measure them.

Per Fannie Mae Guidelines: When calculating gross living area

  • The appraiser should use the exterior building dimensions per floor to calculate the above-grade gross living area of a property.

  • For units in condo or co-op projects, the appraiser should use interior perimeter unit dimensions to calculate the gross living area.

  • Garages and basements, including those that are partially above-grade, must not be included in the above-grade room count.

Most appraisers will use ANSI standards for measuring. ( American National Standards Institute)

The measurements are done on the exterior rather than the interior except for when there is a second floor. If there is a second floor then the measurements are calculated from common exterior walls and then the appraiser will measure the second floor from the interior and will add about 6 inches to account for the exterior wall.

The open areas of second floors are not counted as living area however the stair areas are included. ANSI standards have a 7 ft ceiling height requirement for living area to be counted. We often see attic areas that have been converted to living areas. This finished attic area must have a 7 ft ceiling to be counted in the GLA. Often the attic area ceiling will be sloped. Portions of the attic area will not have a 7 ft ceiling and per ANSI standards the portions of the sloped area below 5 ft will not be counted as living area.. As stated above, garages and basements are not included in the square footage as well as other unfinished areas in the home. If there is detached living quarters, such as a guest house, this will not be included in the living area. Enclosed or Screened porches or converted garages will not be included unless they are converted in the same workmanship as the rest of the home and are heated and cooled. These areas will be measured and will have some value attributed but cannot be included in the GLA (gross living area) calculation of the home.

Appraiser Measurement vs. Tax Record or MLS Measurment

Sometimes the gla measurement of your home located on your Tax Record or MLS data will be different that the appraiser measurement. Here are few reasons why:

  • The tax office typically doesn't physically measure your home. There data may come from original building plans or aerial view thus it is more of an estimate.

  • Sometimes additions to your home have been done and have not been included in the tax record.

  • The original building plans provided to the tax office were incorrect.

  • Perhaps the MLS or Tax Record have included a guest house, basement or finished attic space that are not included in appraiser measurement.

  • An addition that is not of the same quality of workmanship as the rest of the house. Sometimes we see additions or enclosed porches that are not of the same quality of workmanship of the rest of the house. This may be included in the Tax Records but will not be included in Appraiser measurement.

It is very important to get the calculations correct. We have seen tax records be more than 500 sq ft different from our measurements. If you have questions about the accuracy of your gla measurement we suggest that you hire an appraiser or someone who has experience measuring homes.

Let us know your thoughts and if you have any questions please contact us at

Disclaimer: All information deemed reliable but not guaranteed. The information is meant entirely for educational purposes and casual reading only and is NOT intended for any other use. This information is NOT intended to support an opinion of value for your appraisal needs or any sort of value conclusion for a loan, litigation, tax appeal or other potential real estate or non real estate purpose. If you’d like to obtain additional information or order an appraisal for your specific needs, please contact us at

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