BOMA Standards   

Building Owners and Managers Association

For over a 100 years, BOMA International has set the standard for measuring buildings. In 1915, BOMA first published the Standard Method of Floor Measurement for Office Buildings, an accepted and approved methodology by the American National Standards Institute. Throughout the years, the standard has been revised to reflect the changing needs of the real estate market and the evolution of office building design. Today, BOMA International is the secretariat of a suite of measurement standards: 

Standard Methods of Calculation

  • BOMA Standard for OFFICE Buildings (ANSI/BOMA Z65.1 -2017)
    • The objective of the office standard is to provide a uniform basis for measuring Rentable Area in both existing and new multi story, multiple occupant buildings by taking a building-wide approach to floor area measurement. There are two methods within the standard that could be used to calculate the load factor used to assign common area among tenants used to calculate the Rentable Area.
      • METHOD A - Legacy Method (multiple add-on factors - per floor)​
      • ​METHOD B - Single Load Factor (entire building)

  • BOMA Standard for INDUSTRIAL Buildings (ANSI/BOMA Z65.2-2012)
    • ​The objective of this standard is to measure space for the calculation of Rentable Area in both new and existing industrial spaces.  One of two methods may be used in this calculation guided by the dominant market practices of the area.

      • METHOD A - Exterior Wall Methodology
      • METHOD B - Drip Line Methodology 
  • ​​BOMA Standard for RETAIL Buildings (ANSI/BOMA Z65.5-2010)
    • This standard of measurement is intended for application to buildings containing retail type occupancies relevant to both new and existing buildings whether single or multiple stories. Construction Gross Area, Exterior Gross Area and Gross Leasable Area are clearly defined.

  • BOMA Standard for MULTI-UNIT RESIDENTIAL Buildings (ANSI/BOMA Z65.4-2010)
    • ​This standard provides an unequivocal direct measure of the physical size of the floor area of a multi unit-residential Building resulting in Unit Gross Area and Unit Net Area using two measurement methods:
      • METHOD A - ​Gross Method
      • METHOD B - Net Method 
  • ​​BOMA Standard for GROSS AREA of a Building (ANSI/BOMA Z65.5-2018)
    • ​The Exterior Gross Area is the total floor area contained within the measure line. - generally the outside surface of the exterior enclosure of a building - including structured parking. Use for single tenant Offie Buildings 
  • BOMA Standard for MIXED USE Properties (ANSI/BOMA Z65.6-2012)
    • ​BOMA's newest measurement standard provides the ability to measure the Exterior Gross Area of use components for which BOMA International does not publish specific measurements standards, such as hotels, theaters, institutional and civic use and of parking components. Measure the exterior gross area for use components for office, industrial, retail and multi-unit residential use components, for which Rentable Area, Gross Leasable Area or Unit Areas are individually measurable using measurement standards published by BOMA.


Square Footage - Method for Calculating: ANSI Z765-2013

One of the most important indicators of a home’s worth is its square footage. An American National Standard from the National Association of Home Builders (NAHB) Research Center helps homeowners and real estate professionals make accurate appraisals of a property’s size. ANSI Z765-2003, Single-Family Residential Buildings - Square Footage - Method for Calculating, suggests measuring and multiplying the home’s exterior dimensions, then subtracting unfinished space, rooms that are not usable year-round, and rooms with a sloping ceiling. An additional differentiation is made between above-grade and below-grade square footage. Armed with an accurate appraisal, sellers can decide if renovations and other home improvement projects will add substantially to the worth of their property.



The Real Estate market centers on a key piece of information, square footage. This is important for new construction as well as existing buildings. Using our guaranteed accurate as-built plans and CAD file, we can easily calculate useable area, rentable area, gross leasable area and gross square footages to industry accepted BOMA standards or standards of your choice. We are versed in industry accepted standards for the Commercial, Retail, Industrial, Residential, Mixed Use and Condominium properties. Accurate square footage numbers are crucial to any Real Estate transaction whether it is buying, selling, leasing, tax appraisals, building management services, or construction.  The truth will set you free!