What is the difference between gross floor area and gross square footage?

In everyday use there is usually no difference. Both mean the total floor area of a building measured to the outside of its exterior walls, counting every floor. What changes is who defines the term and what they choose to leave out.

Gross floor area is the phrase you see most in commercial property and building plans. Gross square footage is the same idea stated in square feet, and people often use it for houses. Neither has one national definition, so the lease, contract, or standard that uses the number decides whether basements, garages, or mechanical space are in it.

Gross living area is narrower than both. It keeps the exterior measurement but counts only finished, above-grade living space, so garages, unfinished areas, and basements are left out even though they sit inside the building.