Timezone acronyms and abbreviations

A time zone is a region on Earth that has a uniform standard time for legal, commercial, and social purposes. It is convenient for areas in close commercial or other communication to keep the same time, so time zones tend to follow the boundaries of countries and their subdivisions.

Most of the time zones on land are offset from Coordinated Universal Time (UTC) by a whole number of hours (UTC−12 to UTC+14), but a few are offset by 30 or 45 minutes. Some higher latitude countries use daylight saving time for part of the year, typically by changing clocks by an hour. Many land time zones are skewed toward the west of the corresponding nautical time zones. This also creates a permanent daylight saving time effect.

Alphabetically sorted. Note that some of the abbreviations are not unique, these will have several entries in the list. Other time zones have many common names, and each of these will be listed as well.

AbbreviationFull nameLocationTimezone
AAlpha Time ZoneMilitaryUTC + 1 hour
ACDTAustralian Central Daylight TimeAustraliaUTC + 10:30 hours
ACSTAustralian Central Standard TimeAustraliaUTC + 9:30 hours
ADTAtlantic Daylight TimeNorth AmericaUTC – 3 hours
AEDTAustralian Eastern Dayl. Time or Australian Eastern Summer TimeAustraliaUTC + 11 hours
AESTAustralian Eastern Standard TimeAustraliaUTC + 10 hours
AKDTAlaska Daylight TimeNorth AmericaUTC – 8 hours
AKSTAlaska Standard TimeNorth AmericaUTC – 9 hours
ASTAtlantic Standard TimeNorth AmericaUTC – 4 hours
AWDTAustralian Western Daylight TimeAustraliaUTC + 9 hours
AWSTAustralian Western Standard TimeAustraliaUTC + 8 hours
BBravo Time ZoneMilitaryUTC + 2 hours
BSTBritish Summer TimeEuropeUTC + 1 hour
CCharlie Time ZoneMilitaryUTC + 3 hours
CDTCentral Daylight TimeAustraliaUTC + 10:30 hours
CDTCentral Daylight TimeNorth AmericaUTC – 5 hours
CEDTCentral European Daylight TimeEuropeUTC + 2 hours
CESTCentral European Summer TimeEuropeUTC + 2 hours
CETCentral European TimeEuropeUTC + 1 hour
CSTCentral Summer TimeAustraliaUTC + 10:30 hours
CSTCentral Standard TimeAustraliaUTC + 9:30 hours
CSTCentral Standard TimeNorth AmericaUTC – 6 hours
CXTChristmas Island TimeAustraliaUTC + 7 hours
DDelta Time ZoneMilitaryUTC + 4 hours
EEcho Time ZoneMilitaryUTC + 5 hours
EDTEastern Daylight TimeAustraliaUTC + 11 hours
EDTEastern Daylight TimeNorth AmericaUTC – 4 hours
EEDTEastern European Daylight TimeEuropeUTC + 3 hours
EESTEastern European Summer TimeEuropeUTC + 3 hours
EETEastern European TimeEuropeUTC + 2 hours
ESTEastern Summer TimeAustraliaUTC + 11 hours
ESTEastern Standard TimeAustraliaUTC + 10 hours
ESTEastern Standard TimeNorth AmericaUTC – 5 hours
FFoxtrot Time ZoneMilitaryUTC + 6 hours
GGolf Time ZoneMilitaryUTC + 7 hours
GMTGreenwich Mean TimeEuropeUTC
HHotel Time ZoneMilitaryUTC + 8 hours
HAAHeure Avancée de l’AtlantiqueNorth AmericaUTC – 3 hours
HACHeure Avancée du CentreNorth AmericaUTC – 5 hours
HADTHawaii-Aleutian Daylight TimeNorth AmericaUTC – 9 hours
HAEHeure Avancée de l’EstNorth AmericaUTC – 4 hours
HAPHeure Avancée du PacifiqueNorth AmericaUTC – 7 hours
HARHeure Avancée des RocheusesNorth AmericaUTC – 6 hours
HASTHawaii-Aleutian Standard TimeNorth AmericaUTC – 10 hours
HATHeure Avancée de Terre-NeuveNorth AmericaUTC – 2:30 hours
HAYHeure Avancée du YukonNorth AmericaUTC – 8 hours
HNAHeure Normale de l’AtlantiqueNorth AmericaUTC – 4 hours
HNCHeure Normale du CentreNorth AmericaUTC – 6 hours
HNEHeure Normale de l’EstNorth AmericaUTC – 5 hours
HNPHeure Normale du PacifiqueNorth AmericaUTC – 8 hours
HNRHeure Normale des RocheusesNorth AmericaUTC – 7 hours
HNTHeure Normale de Terre-NeuveNorth AmericaUTC – 3:30 hours
HNYHeure Normale du YukonNorth AmericaUTC – 9 hours
IIndia Time ZoneMilitaryUTC + 9 hours
ISTIrish Summer TimeEuropeUTC + 1 hour
KKilo Time ZoneMilitaryUTC + 10 hours
LLima Time ZoneMilitaryUTC + 11 hours
MMike Time ZoneMilitaryUTC + 12 hours
MDTMountain Daylight TimeNorth AmericaUTC – 6 hours
MESZMitteleuroäische SommerzeitEuropeUTC + 2 hours
MEZMitteleuropäische ZeitEuropeUTC + 1 hour
MSDMoscow Daylight TimeEuropeUTC + 4 hours
MSKMoscow Standard TimeEuropeUTC + 3 hours
MSTMountain Standard TimeNorth AmericaUTC – 7 hours
NNovember Time ZoneMilitaryUTC – 1 hour
NDTNewfoundland Daylight TimeNorth AmericaUTC – 2:30 hours
NFTNorfolk (Island) TimeAustraliaUTC + 11:30 hours
NSTNewfoundland Standard TimeNorth AmericaUTC – 3:30 hours
OOscar Time ZoneMilitaryUTC – 2 hours
PPapa Time ZoneMilitaryUTC – 3 hours
PDTPacific Daylight TimeNorth AmericaUTC – 7 hours
PSTPacific Standard TimeNorth AmericaUTC – 8 hours
QQuebec Time ZoneMilitaryUTC – 4 hours
RRomeo Time ZoneMilitaryUTC – 5 hours
SSierra Time ZoneMilitaryUTC – 6 hours
TTango Time ZoneMilitaryUTC – 7 hours
UUniform Time ZoneMilitaryUTC – 8 hours
UTCCoordinated Universal TimeEuropeUTC
VVictor Time ZoneMilitaryUTC – 9 hours
WWhiskey Time ZoneMilitaryUTC – 10 hours
WDTWestern Daylight TimeAustraliaUTC + 9 hours
WEDTWestern European Daylight TimeEuropeUTC + 1 hour
WESTWestern European Summer TimeEuropeUTC + 1 hour
WETWestern European TimeEuropeUTC
WSTWestern Summer TimeAustraliaUTC + 9 hours
WSTWestern Standard TimeAustraliaUTC + 8 hours
XX-ray Time ZoneMilitaryUTC – 11 hours
YYankee Time ZoneMilitaryUTC – 12 hours
ZZulu Time ZoneMilitaryUTC

The decrease in daylight during the winter months is due to Earth’s axial tilt of 23 degrees. If the Earth was not tilted on it’s axis, the length of day and night would remain steady year long. During winter in the northern hemisphere there is less daylight hours, and the southern hemisphere in turn has longer daylight hours and experiences summer.

The main purpose of Daylight Saving Time (called “Summer Time” in many places in the world) is to make better use of daylight. In Ireland we advance our clocks forward by one hour in Spring to maximise daylight for the summer months. This has the effect of moving an hour of daylight from the morning to the evening. In Winter the clocks are then changed back by one hour to maximise daylight during morning hours.