Guides · Floor Plan Measurement
ANSI Z765 is the American National Standard for measuring residential square footage. Since April 2022 Fannie Mae and Freddie Mac require all conventional loan appraisers to follow ANSI Z765-2021. Understanding the standard is essential for appraisers, agents, and anyone interpreting a residential floor plan measurement.
ANSI Z765 (full title: "Square Footage: Method for Calculating: ANSI Z765-2021") is published by the National Association of Home Builders and approved by the American National Standards Institute. It defines exactly how to measure and report residential square footage so any two appraisers applying it to the same property get the same result. Before mandatory adoption, practices varied widely: one appraiser might include the finished basement, another wouldn't.
Exterior measurement: GLA must be measured from the exterior walls. Interior wall-to-wall measurements are not compliant. Above-grade only: Space is above-grade only if the floor level is at or above finished exterior grade on all sides. Walk-out and daylight basements are below-grade regardless of exposure. Finished space only: Permanent walls, floor covering, and ceiling required. Rough framing or unfinished mechanical rooms excluded. 7-foot ceiling minimum: The majority of a space's floor area must have ≥7-ft ceilings. Areas below 5 feet don't count at all. 5–7 ft areas count only as part of a larger finished space. Cape Cod knee-wall rooms measured only where ceiling exceeds 5 feet. Heated and cooled: Connected to HVAC system. Three-season porches and unheated rooms excluded.
Basement and below-grade space (reported separately). Attached or detached garages. Unheated porches and three-season rooms. Carports. Attic space below 5-foot ceiling height. Utility rooms with inadequate ceiling height.
1. Trace the exterior perimeter of each above-grade finished floor: click the outside face of exterior walls. 2. Exclude the garage; draw it as a separate polygon if needed. 3. Exclude unheated areas. 4. For steeply sloped ceilings (finished attics, Cape Cod rooms), only include floor area where ceiling exceeds 5 feet.
Starting April 2022 ANSI Z765 compliance became mandatory for all Fannie Mae/Freddie Mac appraisals. Appraisers who don't follow the standard risk having appraisals rejected by lenders. This mandate has made consistent, reproducible floor plan measurement tools increasingly valuable for appraisers and the agents they work with.
Ready to measure your floor plan?
Upload your floor plan and trace square footage in any browser: no software required.
Start Measuring →What is ANSI Z765?
ANSI Z765 is the residential square footage measurement standard required by Fannie Mae and Freddie Mac for all conventional appraisals since April 2022. It defines Gross Living Area (GLA) as above-grade, finished, heated and cooled living space measured from the exterior of the walls, with a minimum 7-foot ceiling height.
Does basement count toward ANSI Z765 GLA?
No. Below-grade space, including a fully finished basement, is excluded from GLA under ANSI Z765 regardless of finish quality. Finished basements are reported separately as Below-Grade Finished Area.
Why exterior measurement instead of interior?
Exterior measurement is reproducible from outside the building, captures the full footprint including wall thickness, and matches how building permits and assessor records are typically recorded. Interior measurement undercounts by the cumulative thickness of all exterior walls.
What ceiling height is required to count toward GLA?
ANSI Z765 requires a minimum ceiling height of 7 feet, with at least 50 percent of the room area at 7 feet or higher. Sloped ceiling areas (like attic conversions) only count where the height meets that 7-foot minimum.
Is ANSI Z765 mandatory for all appraisals?
It is mandatory for conventional residential appraisals submitted to Fannie Mae or Freddie Mac as of April 2022. FHA, VA, and USDA loans have their own variations but largely align with ANSI Z765 methodology.