Building Area Calculations

Building Area Calculations

DG&S produces assignable area measurement reports using either the RICS code of measuring practice or the recently introduced IPMS guidelines. This can be performed using the clients existing drawings or as part of an existing survey.


The basis for area calculation measurement is for planning applications and approvals, ratings of warehouses and industrial buildings, building cost for residential property for insurance purposes and for marketing and valuation of any commercial and industrial buildings including offices, department stores, food superstores, etc.


  • The RICS code of measuring practice contains a hierarchy of definitions and the core definitions are:

Gross External Area (GEA)

  • The area of the building measured externally at each floor level.

Gross Internal Area (GIA)

  • The area of a building measured to the internal facade of the perimeter at each floor level.

Net Internal Area (NIA) 

  • The usable area within a building measured to the internal facade of the perimeter walls to each floor level.

An example of a building area calculation from a recent project
Due to the different measuring techniques for properties around the world, the probability of property floor area deviation is high. So to enhance transparency and consistency in the methods for property measurement, IPMS was introduced in November 2014.

IPMS (International Property Measurement Standards)

  • IPMS is an International property measurement standard introduced in November 2014 and it represents a major technical advancement in property measurement profession. It is a global standard developed to make property measurement internationally consistent.

IPMS calculations are divided into three categories, which are as follows:

IPMS 1 (Equivalent to GEA) 

  • IPMS 1 is the sum of the areas of each floor level of a building measured to the outer perimeter of external construction features and reported on a floor-by-floor basis. IPMS 1 is categorised the same for all classes of building.

IPMS 2 – Office (Equivalent to GIA)

  • IPMS 2 – Office is the sum of the areas of each floor level of an office building measured to the internal dominant face and reported on a component-by-component basis for each floor of a building.

IPMS 3 – Office (Equivalent to NIA)

  • IPMS 3 – Office is the floor area available on an exclusive basis to an occupier, but excluding standard facilities and shared circulation areas, and calculated on an occupier-by-occupier or floor-by-floor basis for each building.

DG&S can use both RICS code of measuring practice and IPMS to prepare assignable area measurement reports.

Contact us now for a conversation about your project requirements