Gross leasable area (GLA) is the total enclosed floor area designed for the exclusive use of an occupant, including any basements, mezzanines, or upper floors. It is measured from the center-line of partitions that separate adjacent occupants, from the line of the exterior surface of exterior enclosures, from the lease line at common areas, including the full thickness of all other enclosing walls. No deduction is made for columns, structural elements or occupant void areas within the GLA.
According to BOMA (Building Owners and Managers Association), it is not uncommon for the measurement and calculation by one party to differ from the the measurement and calculation by another party of the same area. The calculation for an area, resulting from site measurement by the building owner or manager, is deemed accurate if a re-measurement gives a result with a variance of two percent (2%) or less.