The Common Area Ratio (CAR) is an indicator used to distribute common areas of a building between owners or tenants. CAR takes into account areas that are in common use (corridors, stairwells, elevator lobbies) and is used in both residential and commercial real estate.

Application of the common area ratio:

  • In commercial real estate. The CAR is used to calculate the rentable area in buildings with common areas such as corridors, lobbies, stairwells and service areas. Often the CAR is expressed as a percentage and added to the net rentable area of ​​the tenant.
  • In multifamily buildings. Here the coefficient helps to determine what share of the common areas (stairs, elevators, corridors, attics, basements) each apartment pays for. It is used when calculating utilities or other costs.
  • In building design. Architects and designers use this indicator to optimize space, to balance between the total usable area and the necessary auxiliary areas.

For example, the total area of ​​an office center is 1000 m², of which 200 m² are common areas. The common area coefficient allows you to distribute these 200 m² among tenants proportionally to the areas they occupy.

The common area coefficient is calculated as the ratio of the total area of ​​auxiliary premises (e.g. corridors, hallways, stairwells) to the total area of ​​the building, expressed as a percentage. The formula is as follows: the area of ​​auxiliary premises is divided by the total area of ​​the building, and then the result is multiplied by 100 to obtain a percentage.

The calculation takes into account corridors, stairwells, elevator halls and shafts, common technical premises (e.g. server rooms, storage rooms), recreation areas, foyers, and lobbies.

Closed technical premises (e.g. electricity meters, pumping stations) and premises that are not related to residents or tenants (e.g. private technical floors) are not taken into account.