Floor numbering

Lower Floors

Subterranean levels vary in numbering systems, often using B for Basement or P for Parking, for the first level below ground, although L (or LL) for Lower Level is sometimes used. The next level down may be SB for "Sub-Basement", although numbering more frequently occurs at this point, either B1/P1 etc. or use of negative numbers -1 etc.

First Floor

In British English, in reference to typical buildings, the "first floor" is the first floor above the ground; but in American English, it is another name for the ground floor.

Most European countries, countries of the Commonwealth, and former British colonies like Hong Kong, follow the same convention as the British, although Russia, some countries of East Europe, and Japan follow the American convention. Hong Kong is unusual in that it follows the British rule in English, but for some old tenament buildings the Chinese glyphs follow the American rule.

Higher floors are then numbered consecutively in each case, as illustrated by the following table:

British convention American convention Hong Kong convention
3rd floor 4th floor 3rd floor (and 三樓, 四樓 (literally 4th floor) for old tenant buildings)
2nd floor 3rd floor 2nd floor (and 二樓, 三樓 (literally 3rd floor) for old tenant buildings)
1st floor 2nd floor 1st floor (and 一樓, 二樓 (literally 2nd floor) for old tenant buildings)
Ground floor Ground or 1st floor Ground floor and 地下 (literally Ground floor)

It is obvious that this can lead to some confusion, but little else can be done other than being aware of this issue. Put simply:

  • American English floor number minus 1 = British English name
  • British English floor number plus 1 = American English name

In North America, some buildings may have entrances on two different floors, such as those built into a hill. In these cases, the ground floor is the lower and the first floor is the upper. Also, some U.S. high-rise buildings follow the British system, often out of a desire on the part of the building's architect or owners to suggest a posh U.K./European setting.


Unusual numbering exists in some hotels, for example, the uppermost level may be PH (for Penthouse), R (for Roof), or O (for Observation Deck), and the entrance level may sometimes be denoted M (for Main), or L (for Lobby). However, some buildings use extremely idiosyncratic denotation - one hotel in Toronto marks the first six floors as A, M, MM, C, H, and 1 (for Arcade, Main, Main Mezzanine, Convention, Health Club, and 1st floor).

It is not uncommon for American buildings to omit the number 13 in their floor numbering because of common superstition surrounding this number. The floor numbering may either go straight from 12 to 14, or the floor may be named something like 'Skyline' instead of numbered. See Thirteenth floor for more details. In Hong Kong some buildings would omit 4th, 14th, 24th, etc floor as the number 4 sounds like death in Cantonese, but the rule is varied.


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