Learn · Real Estate · 7 min read

Part of: Square Footage in Real Estate: The Complete Guide

Deed Square Footage vs Appraisal: Why the Numbers Are Different

County records say 2,200 square feet. The appraiser says 1,950. The MLS said 2,100. All three numbers can exist on the same property — and all three can be defensible. Here's why they diverge and which one actually matters for your mortgage.

Where deed and county record square footage comes from

The square footage that appears on a deed, tax record, or county assessor database typically originates from one of three sources: the builder's plans at the time of construction, a permit application, or a tax assessor's field measurement taken decades ago. None of these are held to the same measurement standard that appraisers use today.

Assessor measurements are often taken from exterior dimensions using aerial imagery, county GIS data, or a drive-by measurement without entering the property. These methods produce estimates, not precise floor-level measurements. Garages, basements, and unfinished spaces are sometimes included and sometimes not, depending on the assessor's methodology — which varies by county and can change over time.

The result is that county-recorded square footage is frequently wrong, often by 5% to 15%, and occasionally by much more. This is so common it has its own dedicated problem: see what to do when county assessor square footage is wrong.

How appraisers measure square footage

A licensed appraiser measures the home in person, on-site, using the exterior dimensions of each level. They follow ANSI Z765-2021, the national standard that Fannie Mae requires for all conventional loan appraisals. This standard defines exactly what counts as gross living area: finished, above-grade space suitable for year-round use. Garages, unfinished basements, screened porches, and below-grade finished areas are all excluded from GLA, even if they were included in a prior square footage figure.

The appraiser's measurement is the most reliable number in the chain. It's taken by a licensed professional, follows a defined standard, and is the number a lender will use to underwrite your loan.

Which number lenders use: The appraiser's GLA figure — always. Deed square footage, assessor records, and MLS data are not used for underwriting decisions. If the appraisal GLA differs significantly from other sources, the lender relies on the appraisal.

Source	Measurement Method	Includes Garage/Basement?	Lender Relies On?
Appraisal (GLA)	Exterior, ANSI Z765	No — excluded from GLA	Yes — primary
County assessor	Aerial/GIS estimate or old field measure	Often yes	No
Deed / public record	Varies — often from builder plans or permits	Sometimes	No
MLS listing	Agent-entered, source varies	Varies	No
Builder plans	Interior dimensions (no wall thickness)	Depends on plans	No

Common reasons the numbers diverge

Different spaces are included

The most common reason for a discrepancy is that the deed or assessor figure includes space that an appraiser excludes. An attached garage adds 400 to 600 square feet. A finished basement adds more. If those spaces were folded into the county's total and the appraiser correctly excludes them, the gap is explained immediately — and the appraiser is right.

Measurement method differences

Exterior measurements (used by appraisers) include wall thickness. Interior measurements (sometimes used by builders or assessors) do not. On a 2,000 sq ft home, this difference can be 100 to 200 square feet — entirely explainable by method, not error.

Unpermitted additions

If a prior owner added a room or finished a space without a permit, that space may not appear in county records at all, or may appear incorrectly. Appraisers measure what they find and then make a judgment on whether unpermitted space qualifies as GLA. For more on this, see the guide on unpermitted square footage in appraisals.

Outdated assessor data

Many counties update assessor records only when a property sells or is significantly remodeled. A home that was modified, reconfigured, or partially demolished between assessment cycles may have a county square footage figure that is years or decades out of date.

Rounding and transcription errors

Square footage gets rounded, estimated, and re-entered into databases at multiple points across a property's history. A builder's plan says 1,847 sq ft. A permit says 1,850. The assessor enters 1,900. The listing agent rounds up to 1,950. Each step introduces drift, and by the time the appraiser shows up with a tape measure, the number in the MLS is meaningfully different from reality.

What a big discrepancy means for a sale or refinance

If the appraiser's GLA is significantly lower than what was advertised in the listing, the appraisal value may come in below the contract price. Lenders base loan amounts on the lower of the sale price or appraised value, so a low appraisal can derail financing or force a price renegotiation.

A square footage discrepancy can also constitute material misrepresentation in a real estate transaction if a seller or agent knowingly advertised an inflated figure. Buyers who discover a significant gap after closing have pursued legal remedies in some markets, particularly when the square footage disclosure was inaccurate.

For a refinance, a lower GLA figure than what was used in the original purchase appraisal is less likely to cause problems unless it pushes the loan-to-value ratio above the lender's threshold. But a large drop can still trigger questions. If you're pulling equity through a home equity loan or HELOC, the appraiser will remeasure GLA — a discrepancy from county records can affect how much equity you can access.

How to check before listing or buying

If you're selling, the safest move is to have a floor plan measured before you list. If your county records show a number that seems high, verify it yourself rather than advertising the inflated figure. A discrepancy discovered by the buyer's appraiser during escrow is far more disruptive than one caught beforehand.

If you're buying, don't rely on the MLS square footage or the county records. Both are self-reported or estimated. The appraisal ordered by your lender is the only figure in the transaction that reflects an independent, standards-based measurement. If you want your own verification before the appraisal, see the full guide on how to verify square footage before buying.

Can you correct the deed or county records?

Yes, in most jurisdictions, and it's worth doing if the error is significant. Most county assessor offices have an appeal or correction process. You'll typically need to provide a copy of an appraisal, a survey, or a professional measurement to support the correction request. The assessor's office may send someone to re-measure, or they may accept your documentation and update the record administratively.

Correcting an inflated square footage in county records can actually reduce your property tax bill if the assessment was based on the overstated figure — an outcome most homeowners are happy to pursue. For more on the connection between recorded square footage and tax assessments, see square footage and property taxes.

Bottom line:

Deed / county records: estimated, often outdated, not used for lending
MLS listing: self-reported, frequently copied from county records, not verified
Appraiser GLA: measured on-site, follows ANSI Z765, used by lenders
If they conflict: the appraiser's number governs the loan

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Related Resources

Frequently Asked Questions

Why does deed square footage differ from an appraisal?

Deed square footage, if it appears at all, is often from assessor records that may be decades old, measured differently, or based on building permits rather than actual field measurement. Appraisers measure to ANSI Z765 standards, which may produce a different number than what is on file.

Which is more accurate: deed square footage or appraisal?

The appraisal is more accurate for lending purposes. It reflects a current ANSI Z765 exterior measurement by a licensed professional. Deed and assessor records use older data, different measurement methods, and may not account for additions or corrections.

Can deed square footage affect a home sale?

Yes. If a listing relies on deed square footage that overstates the actual GLA, the appraisal may come in lower than expected. Buyers and sellers should use appraiser-measured GLA as the authoritative figure, especially when the deed number seems unusually high or low.

How often is county assessor square footage wrong?

County assessor square footage errors are common. Studies suggest that 10% to 20% or more of assessor records contain meaningful discrepancies compared to field-measured GLA. Common causes include garages and basements counted in the total, outdated records that predate additions or demolitions, and measurement methodology differences from decades-old site visits.

What should a buyer do if the appraisal square footage is lower than the listing?

First, understand why the numbers differ. If the difference is a definitional issue (the listing included a finished basement or garage), the appraisal GLA may still support the purchase price. If the appraiser missed finished space or made a measurement error, the buyer can request a Reconsideration of Value with documented measurements. Lenders use the appraisal GLA, not the listing figure.

Can I correct incorrect square footage in county records?

Yes. Most county assessor offices have a formal correction or appeal process. You typically need to provide supporting documentation such as a recent appraisal, a survey, or a professional floor plan measurement. If approved, the assessor updates the public record. Correcting an inflated figure can also reduce property taxes if the assessment was based on the overstated square footage.

Does MLS square footage have to match the appraisal?

No. Listing agents enter square footage based on whatever source they have available, which may be county records, prior appraisals, or owner estimates. Lenders do not use MLS square footage for underwriting decisions. A significant gap between MLS and appraisal figures is common and is not automatically a problem unless the listing made material misrepresentations about size.

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Official Sources

The Appraisal Foundation — USPAP — Uniform Standards of Professional Appraisal Practice defining how appraisers must measure, document, and report gross living area.
Fannie Mae Selling Guide B4-1.3-05 — Property and Appraisal Analysis — Fannie Mae standards for GLA measurement and acceptable divergence between appraiser and public record square footage.

More guides on square footage in real estate:

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