Appraisal Fundamentals
How Appraisers Measure a House
The standardized method behind the square-footage figure in your appraisal report.
The square-footage figure in an appraisal isn't a casual estimate — it follows a specific, repeatable measurement standard so it can be fairly compared to other homes' reported area in the same market.
The Measurement Process
Exterior Perimeter
Most residential appraisals measure the exterior perimeter of the home at the foundation line, following the ANSI Z765 standard that most lenders require for consistency.
Level by Level
Each finished level is measured and diagrammed separately, with any non-living space (garage, unfinished areas) excluded from the living area calculation.
Sketch & Cross-Check
The appraiser produces a floor-plan sketch showing dimensions, which is checked against the calculated area — a useful cross-check against measurement or data-entry errors.
Why the Sketch Matters
The floor-plan sketch included in most reports isn't decorative — it's the appraiser's documented basis for the reported area, and it lets anyone reviewing the report (a lender, an underwriter, a Board of Equalization) verify the calculation rather than take the final number on faith.
What This Does Not Mean
A different number than your county tax record or a builder's marketing brochure doesn't automatically mean either figure is wrong — they're often measuring by different conventions. And a consistent measurement standard is precisely what makes comparable-sales analysis fair across an entire neighborhood.
Frequently Asked Questions
Provided for general educational purposes based on the ANSI Z765 measurement standard commonly required by residential mortgage lenders. Last reviewed: August 2026.