Floor numbering

Floor numbering is the numbering scheme used for a building's floors.

American
In this scheme, the "first" floor is the floor at the ground level and the floor above it is the "second" floor. On some buildings, floors below ground floor are usually marked as basement (B) but some buildings also marked these floors as minus (-), for example; minus one (-1), minus two (-2) and so on. In few cases, the floors below ground floor are marked as lower ground (LG) or sub basement (SB) though this is uncommon.

This scheme is used in some part of the United States and Canada, some Latin American countries, Russia and former Soviet Union countries, China (excluding Hong Kong and Macau), South Korea, Japan, Singapore and parts of Indonesia.

USSR
Buildings in former USSR countries (including those in Europe such as Estonia) often use the North American scheme, but call the storey immediately below the ground floor "0".

European
In this scheme, the "first storey" or "first floor" is the level above ground level. The floor at ground level is usually called "0" or substituted by the first letter of the local language's word for ground (i.e. "G" in Britain or "E" for Erdegeschoss in Germany)

This scheme is used in the United Kingdom, most European countries, Mexico, Cambodia and former British colonies.

There is a set standard as per EN81-70 for the ground floor button to be protrude a different amount & have green coloration to indicate that this is the floor with the quickest route to the outside of the building. This is not always the case, for example in lifts which don't go to the ground floor. The similar term also apply for the "Design Manual: Barrier Free Access 2008 (設計手冊：暢通無阻的通道 2008, BFA 2008)" standard by Buildings Department in Hong Kong, China. A "star" (☆) is often included in the ground floor button to indicate a main entrance level.

Minus (-)
Minus (-) is used to depict floors below ground floor. Sometimes minus is used as a substitution to basement(B), lower ground (LG) or sub basement (SB). Minus is also commonly used in buildings with destination dispatch elevators.

A
A is usually used to depict an extra floor, such as 3A being an additional third floor. It is also used to depict an apartment floor. Sometimes, it can be used to omit unlucky floor numbers.

B
B also known as basement, usually used to depict floors below ground floor. It is widely used in most buildings. An additional basement below is often marked as LB while above is UB.

UB may also means which is an extra "base" floor above the ground floor.

Meaning of basement in foreign countries by their native language:
 * K: Keller (German), Kelder (Dutch/Estonian), Kælder (Danish), Kjeller (Norwegian), Källare (Swedish), Kellari (Finnish)
 * S (Spain): Sótano
 * SS (France): Sous-sol (Portuguese): Subssolo
 * P: Porão (Portugese), Piwnica (Polish)
 * U (Germany): Untergeschoss ("Underfloor")
 * П: Подвал (Russian), Падвал (Belarussian), Підвал (Ukrainian)
 * М (Bulgaria): Мазе
 * υ (Greece): υπόγειο

G
G or GF usually means ground floor. This floor numbering is widely used in buildings using European scheme. In some case, the letter G may be replaced into zero (0) in Europe or one (1) in America. A "star" (☆) is often included in the ground floor button to indicate a main entrance level. In foreign countries, ground floor is usually referred to by their native language, for example:
 * BG (Dutch): begane grond (lit. "walked-upon ground")
 * BV (Swedish): Bottenvåning ("ground floor")
 * D (Indonesia): dasar/lantai dasar ("ground floor")
 * E (Germany): Erdgeschoss ("ground floor") (Swedish): Entrévåning ("Entrance floor")
 * PB (Spain): planta baja or planta baixa ("bottom floor")
 * PT (Italy): piano terra (lit. "ground floor")
 * RC (France): rez-de-chaussée ("street level")
 * S (Danish): Stuen ("ground floor")
 * T (Brazil): Térreo (Ground)
 * P, PK (Finland) Pohjakerros ("ground floor")
 * כ (Israel): כניסה ("Entrance")
 * ק (Israel): קרקע ("Ground")
 * ι (Greece): ισόγειο ("ground floor")

L
L or LB usually means lobby or level, e.g. level 1 is marked as L1. In some buildings with an additional lobby or certain floor below the ground floor, it is usually marked as LL (lower lobby or lower level). As same as "ground floor" (G), a "star" (☆) is often included in the lobby button for the elevator installed in the America to indicate a main entrance level.

The another variant of the "lobby" is UL, means upper level, common in 2 floor buildings like shopping malls, dept. stores and supermarkets, but can also stand for upper lobby, which is an extra "lobby" floor above the main lobby floor. An example of the building that uses UL floor is Interchange 21, Bangkok

LG
LG usually means lower ground, which is an extra "ground" floor below the main ground floor. In some cases, lower ground can be more than one floor, but usually not more than five lower ground floors (e.g. LG1 and LG2). Example of buildings with more than one lower ground floor are Festival Walk in Hong Kong and ifc Mall in Shanghai.

The other variant of the floor LG maybe substituted as floor -0.

M
M or MZ is commonly known as mezzanine, which is an intermediate floor between main floors of a building. A lower mezzanine is often marked as LM, or a mezzanine ground is often marked as MG though this is uncommon. In rare cases, it may refer to metro.

P
P may refer to as parking (for multi-purpose building with the floors for car park or parking garage), pool (in some hotels), podium (the leisure spaces in the housing estate, but built above ground floor), or platform(usually appeared in train station) floor. Multiple parking floors are usually marked as P1, P2 and so on. CP may also be used, meaning "car park", or PL, meaning podium level or pool level.

R
R is usually known as roof or rooftop. Sometimes RF may also be possible to be used.

UG
UG means upper ground which is an extra "ground" floor above the main ground floor.

Other floor numberings

 * C: Concourse, used in some train stations and double deck (lower deck) elevator or Casino, in Casinos.
 * F/FB: Footbridge, used in some pedestrians footbridge.
 * H: Helipad or other special floor.
 * PH: Penthouse floor.
 * S or SL: Street level, used in some train stations, or Subway, for some pedestrian tunnels.
 * T: Terrace, used in some apartment buildings.
 * MTR: Abbreviation of Mass Transit Railway (MTR) in Hong Kong, China. For the floor in the adjacent building directly connected to the MTR station.
 * BB: Breakfast Buffet
 * X and E: 10th and 11th floors in Duodecimal towers of Liftland