Buying a Home · 6 min read

How to Verify Square Footage Before Buying a Home

The square footage on a listing is often wrong. It might be an honest mistake, a stale county record, or an intentional stretch to justify a higher asking price. Before you close, here is how to independently verify the number.

Why MLS square footage is often inaccurate

Most real estate listings pull square footage from county assessor records or from the seller. Neither source is reliable. Assessor data is frequently years out of date, does not distinguish GLA from finished basement area, and uses different measurement methods than appraisers do. Seller-reported figures are often estimates, rounded generously, or simply copied from old listings.

A 2022 study by CoreLogic found that square footage discrepancies of 5% or more exist in a meaningful portion of residential transactions. On a 2,000 sq ft home at $250 per square foot, a 5% error is $25,000.

Step 1: Request the appraisal report

If the seller had the home appraised recently, or if a previous sale triggered a lender appraisal, that report contains a certified GLA measurement. The appraiser measured from the exterior, followed ANSI Z765 methodology, and signed off on the number. This is the most reliable source you can get without ordering your own appraisal.

Ask your agent to request the appraisal from the seller or listing agent. Sellers are not always required to disclose it, but in a negotiation it is a reasonable ask.

Step 2: Check county assessor records

The county assessor's office maintains records for every parcel. Search your county assessor website by address and look for the "living area," "heated area," or "GLA" field. This number is often the basis for the MLS figure.

The assessor uses this number for tax purposes, not appraisal purposes. The measurement method may differ, and additions or renovations may not be reflected if no permit was pulled. Use it as a sanity check, not a definitive source.

Step 3: Obtain a floor plan and measure it yourself

Request a floor plan from the listing agent, or check if one was provided in the MLS documents. Many listings include a floor plan for marketing purposes. If you have a floor plan with a known scale, you can measure it yourself.

PlanSnapper can calculate square footage from a floor plan image in under two minutes. Upload the floor plan, approve the perimeter, set the scale using any wall dimension you know, and you get an accurate GLA number. This works for any home where you have a floor plan, whether it is a PDF, a photo of a printed plan, or an image from the MLS.

If the floor plan does not have printed dimensions, you can estimate the scale from standard features: exterior doors are typically 3 feet wide, garage doors are 8 or 9 feet wide, standard room widths give you reference points.

Step 4: Walk the home yourself during the inspection

During your inspection period, bring a laser distance measurer. Measure key exterior walls and compare to the floor plan. You do not need to measure every room, but checking two or three exterior wall lengths will tell you quickly whether the overall scale is right.

If you measure a 20-foot exterior wall and the floor plan shows it as 20 feet, the scale is accurate. If it shows 24 feet, the floor plan is inflated. You are checking the floor plan, not the home, because the home does not lie.

Step 5: Order an independent appraisal

If the purchase price is heavily influenced by square footage, or if you find a significant discrepancy that the seller will not explain, consider ordering your own appraisal. A licensed appraiser will measure from the exterior, apply ANSI Z765 methodology, and provide a certified GLA figure.

Residential appraisals typically cost $400–700 depending on the market and property complexity. If a square footage dispute stands to affect the deal by more than that, it is worth it. Your lender will order their own appraisal anyway, but having your own number before negotiations end gives you leverage.

What happens if the square footage is wrong

If the listing overstated GLA, you may have grounds to renegotiate the price. Many purchase contracts include representations about property characteristics. A material discrepancy between listed and actual square footage can be a basis for price adjustment or, in some cases, contract termination.

Talk to your real estate attorney if you find a significant error. Even a 100 sq ft discrepancy on a $500K home may be worth addressing before you close.

Learn more

Why does my measurement differ from the assessor or MLS? covers the reasons discrepancies exist and which source to trust. See also Is Zillow square footage accurate?