ANSI Square Footage Calculator

Room Name

Length (ft)

Width (ft)

Floor Level

Finished

What is ANSI Z765?

ANSI Z765-2021 is the American National Standard for measuring residential properties. Published by the Building Owners and Managers Association (BOMA) and adopted by Fannie Mae, it defines exactly what counts as gross living area and how to measure it for appraisal purposes.

Why below-grade areas are excluded from GLA

ANSI Z765 excludes below-grade areas from GLA regardless of finish quality. A finished walkout basement with full amenities does not count toward GLA under ANSI standards. It is reported separately and may receive its own adjustment in the appraisal, but it is never added to above-grade living area.

Common measurement mistakes

Garages, carports, unheated sunrooms, and below-grade spaces are frequently included in advertised square footage but excluded from GLA. Appraisers often find discrepancies between what sellers advertise and ANSI-compliant GLA. Always measure to exterior walls and use ANSI rules to determine what counts.

How lenders use GLA

Fannie Mae, Freddie Mac, FHA, and VA all require appraisers to report GLA using ANSI Z765 standards on standard appraisal forms. The GLA drives comparability decisions, adjustments, and ultimately the appraised value that determines loan eligibility.

Does a finished basement count as GLA?

No. Under ANSI Z765-2021, no below-grade area counts as gross living area regardless of how well it is finished. A finished basement is reported separately on appraisal forms and may receive a positive adjustment compared to comps without finished basements, but it is never added to the GLA total.

What is ANSI Z765?

ANSI Z765-2021 is the current version of the American National Standard for single-family residential property measurement. It defines gross living area, specifies how to measure interior and exterior dimensions, and provides rules for inclusions and exclusions. It is the required standard for Fannie Mae and Freddie Mac appraisals.

How do appraisers measure square footage?

Appraisers typically measure the exterior of the home and calculate area based on exterior dimensions, then subtract garages and other non-GLA areas. Under ANSI Z765, measurements are taken to the nearest inch and area calculations round to the nearest whole square foot. Interior room measurements like those in this calculator are an approximation -- professional measurement accounts for wall thickness.