GLA and Measurement Standards · 5 min read

What Is ANSI Z765 and Why Does It Matter for Appraisals?

ANSI Z765 is the national standard for calculating residential square footage in the United States. If you are a real estate appraiser, agent, or anyone measuring a home for lending purposes, this is the rulebook. PlanSnapper is built to produce measurements that comply with it.

What ANSI Z765 actually is

ANSI stands for the American National Standards Institute. Z765 is the specific standard published by ANSI that covers how to measure and calculate the area of single-family residential buildings. The current version is ANSI Z765-2021.

It was created to bring consistency to residential measurement. Before this standard, appraisers, agents, and builders used different methods, which led to inconsistent square footage figures for the same property. ANSI Z765 defines what counts, what does not, how to measure it, and what to include in a report.

Why Fannie Mae and lenders require it

In 2022, Fannie Mae updated its Selling Guide to require that appraisers follow ANSI Z765-2021 when measuring and reporting square footage for most single-family residential appraisals. This made it a practical requirement for any loan that will be sold on the secondary market.

FHA and VA have their own guidelines, but the ANSI standard is broadly accepted across lender types. When a lender questions a square footage figure, an appraiser who measured to ANSI standards has clear documentation to back their number.

The core rules in ANSI Z765

• Measure from the exterior: GLA is calculated from the outside of exterior walls, not interior wall-to-wall.
• Ceiling height minimum: Finished space must have a ceiling height of at least 7 feet over at least 50% of the area. Sloped ceilings (attics, cape cods) are allowed if they meet the 50% threshold at 7 feet.
• Above-grade only: Below-grade finished space (basements, daylight walkouts below the grade line) is excluded from GLA regardless of finish level.
• Garages are excluded: Attached garages, however finished, do not count as GLA.
• Each level measured separately: Multi-story homes require each qualifying above-grade level to be measured separately, then totaled.
• Rounding: Square footage should be reported to the nearest whole square foot.

What ANSI Z765 does NOT cover

ANSI Z765 covers only above-grade GLA. It does not define how to report basement finished area, accessory dwelling units, or commercial space. Those areas are typically reported separately with a clear label indicating they are not included in GLA.

The standard also does not mandate specific measurement tools. You can use a laser measure, a wheel, or a floor plan with a known scale. What matters is that the result is accurate and you can document how you arrived at it.

How PlanSnapper fits in

PlanSnapper calculates square footage from the exterior perimeter of a floor plan image. Because residential floor plans are typically drawn from the exterior wall face, the number PlanSnapper produces aligns with the ANSI exterior measurement method.

The tool does not automatically exclude garages, basements, or below-grade areas. That is your job. You control what you upload and what perimeter you approve. If you upload only above-grade living area floors and exclude the garage from the perimeter, PlanSnapper gives you a number that matches ANSI methodology.

This is why we note ANSI Z765-2021 compliance on the pricing page. The math follows the standard. The appraiser makes the judgment calls.

Learn more

What counts as GLA in PlanSnapper? and What Is Gross Living Area? go deeper on the GLA definition and how to apply it in PlanSnapper.