Guides · Floor Plan Measurement

How Homebuyers Can Verify Square Footage

The square footage shown on Zillow, the MLS, and county records for the same home often shows three different numbers. As a homebuyer you're making one of the largest financial decisions of your life partly based on square footage. Here's how to verify the number before you make an offer.

Why public numbers are unreliable

County assessor records: Entered by county staff from building permit data. May include basements and garages. May not reflect additions or renovations. Can be decades out of date. Zillow: Pulls from county records or MLS. Inherits whatever errors those sources contain. MLS listing: Agent-entered. Some copy county records; others measure independently; a few include or exclude spaces inconsistently. The only reliable way to know is to measure the floor plan directly.

Step 1 — Get the floor plan

Many listings include a CubiCasa or Matterport floor plan in the listing photos or documents. If not visible, ask your agent to request one from the listing agent. If there's a Matterport tour linked in the listing, the floor plan view is accessible within the tour. For older homes without digital floor plans, your agent can request the prior appraisal (sellers may have one from purchase or refinance).

Step 2 — Measure it

Upload the floor plan to MeasureFloorPlan.com. Trace the above-grade finished living area. Set scale from a labeled room dimension. Read the result. Takes about 5 minutes for a single-story home and 10 minutes for a two-story. You'll have your own verified estimate before making an offer.

What to do if there's a discrepancy

2–5% difference: Normal variation. Note it but don't be alarmed. 5–10% difference: Investigate. Is basement included in the listing number? Unheated spaces? Over 10%: Significant concern. Ask the listing agent to clarify what's included. Factor the corrected sq ft into your offer price. You shouldn't pay above-grade prices for below-grade space.

Better before the offer than after the appraisal

If you discover a discrepancy after your offer is accepted but before the appraisal, you're in a better position than waiting for the appraiser to catch it. Renegotiating based on your own pre-appraisal research is less fraught. Measure first, offer with confidence.