Guides · Floor Plan Measurement

GLA vs Total Square Footage: What Is the Difference?

The same home can have three different square footage numbers depending on who measured it and what they included. Understanding why GLA and total square footage differ is essential for interpreting appraisals, comparing listings, and avoiding surprises at closing.

What GLA includes (and excludes)

GLA (Gross Living Area) = above-grade, finished, heated/cooled space measured from exterior walls. It excludes basements of any finish level, garages, carports, unheated porches, and any below-grade space. This is the number on the Fannie Mae/Freddie Mac appraisal form and the standard used for mortgage lending.

What "total square footage" typically includes

"Total square footage" has no single standard definition. It varies by source: County assessor records often include finished basement and sometimes garage. Definition varies by county. MLS listings are agent-entered — some include basement, some don't. No enforcement of a single standard. Zillow pulls from county records or MLS, inheriting whatever errors and inclusions those sources use.

A concrete example

A home with 1,800 sq ft of above-grade GLA and a 900 sq ft finished basement might appear as: Appraisal GLA: 1,800 sq ft (above-grade only). County assessor: 2,700 sq ft (includes finished basement). MLS listing: 2,700 sq ft (if agent included basement). Zillow: 2,700 sq ft (from county records). The appraiser isn't wrong — they're measuring something different than the county.

Which number to use for what

Mortgage appraisals: GLA required. The appraiser uses above-grade GLA for size adjustments; below-grade finished area gets a separate lower-rate adjustment. Listing square footage: Best practice is to list above-grade GLA and below-grade finished area separately. Many MLS systems now have distinct fields. Lease pricing: Total finished area (including basement) is typically more relevant. Renovation planning: Total finished area for calculating materials, heating load, etc.

How to get both numbers from a floor plan

Upload the floor plan for each level separately. Draw separate polygons for: above-grade floor 1, above-grade floor 2, finished basement, garage. Label each. Sum only above-grade finished polygons for GLA. Add the basement polygon for total finished area. This gives you both numbers from one consistent measurement source.