Accurate Floor Plans and Square Footage: Why the Listing Number Isn't Always Right
Square footage is one of the first numbers buyers look at, and one of the least reliable. Two similar houses on the same street can be listed at very different sizes, and a buyer who measures after closing may find the home is smaller than they thought. Accurate floor plans fix this problem at the source, and they help a listing sell along the way.
Why square footage matters so much
Buyers use size to compare homes, and agents use price per square foot to set and defend a list price. Appraisers and lenders also lean on it. When the number is off, every comparison built on it is off too: the home may be priced against the wrong set of properties, or it may look like a worse deal than it really is.
Where listing numbers actually come from
The figure on a listing doesn't always come from a measurement of the house as it stands today. Common sources include:
Original builder or permit plans, which may not reflect later changes
Public or assessment records, which can be outdated or based on exterior dimensions
The previous listing, copied forward
The seller's estimate or a quick measurement
Many GTA listings also show size as a range instead of a single figure. That keeps things flexible for the listing, but it doesn't help a buyer who wants to know what they're really getting.
Why two "correct" numbers can disagree
Even when everyone measures carefully, the totals can differ, because there's no single rule that everyone uses. The differences usually come down to:
Interior vs. exterior measurement. Measuring to the outside of the walls produces a bigger number than measuring the livable space inside them.
Stairwells and open-to-below areas. Some methods count them, others don't.
Basements and below-grade space. Whether finished lower levels are included, listed separately, or left out changes the total a lot.
Ceiling height and usable space. Low-ceiling or sloped areas may or may not be counted.
Additions and conversions. A rear addition, enclosed porch, or garage conversion may be missing from the older source the number came from.
A good floor plan doesn't just give a total. It shows what was measured, how each level was counted, and where the numbers come from.
What a wrong number costs
An inflated number can make a home look overpriced per square foot, scaring off buyers who would have loved it. An understated number can leave money on the table. And when a buyer, inspector, or appraiser finds a gap, it raises doubts about everything else in the listing, which can slow negotiations or reopen the price.
How accurate floor plans help a listing sell
Buyers trust the numbers. A measured plan with a clear method gives buyers and their agents a reason to believe the figures, which makes negotiation easier.
Buyers understand the layout online. Most buyers shortlist homes from their phones before they ever visit. A clean, accurate floor plan shows how rooms connect, where the stairs go, and how big the bedrooms really are, which photos alone can't do.
Fewer wasted showings. When people can judge the layout in advance, the ones who book a visit are better matched to the home.
A stronger pricing conversation. When the size is documented, an agent can price against truly comparable homes instead of arguing over whose number is right.
A better record of what's actually there. Accurate drawings also capture additions, conversions, and finished spaces, so nothing relevant is overlooked when the home is presented.
What to look for in a floor plan for a listing
Measured on site, not copied from old plans
A clear statement of how area was calculated (interior or exterior, what's included)
Every level shown, with finished and unfinished areas labelled
Room dimensions that match what a buyer would find with a tape
A clean, readable layout that works on a phone screen
A note for agents and sellers
A floor plan documents the space; it doesn't replace your brokerage's rules on how size must be represented in a listing. Check with your brokerage or lawyer on what you're required to disclose and how, and use a measured plan as the factual basis.
Casabuilt measures homes and produces accurate floor plans across the GTA. Send us the address and we'll provide a quote.
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