Time Zones of the World

Time Zones

Because Earth is a rotating sphere, the Sun shines on only half its surface at any time. Thus, it is simultaneously morning, evening, and nighttime in different parts of the world. Because of these disparities, each country or part of a country adheres to a local time. A region of Earth’s surface within which a single local time is used is called a time zone.

Standard Time

Standard time is the official local time in a particular country or part of a country. It is defined by the time zone or zones associated with that country or region. Although time zones are arranged roughly in longitudinal bands, in many places, the borders of a zone do not fall exactly on longitudinal meridians, as can be seen on the map (above). Still, they are determined by geographical factors or borders between countries or parts of countries. Most countries have just one time zone and one standard time, but some large countries (such as the US, Canada, and Russia) are split between several time zones, so the standard time varies across those countries. For example, the coterminous United States straddles four time zones and has four standard times: Eastern, Central, Mountain, and Pacific standard times. China is unusual because just one standard time is used for the whole country, even though it extends across 60° of longitude from west to east.

Coordinated Universal Time (UTC)

Coordinated Universal Time (UTC) is a reference by which the local time in each time zone is set. For example, Australian Western Standard Time (the local time in Western Australia) is set 8 hours ahead of UTC (it is UTC+8), whereas Eastern Standard Time in the United States is set 5 hours behind UTC (it is UTC-5). UTC is a successor to, and closely approximates, Greenwich Mean Time (GMT). However, UTC is based on an atomic clock, whereas GMT is determined by the Sun’s position in the sky relative to the 0° longitudinal meridian, which runs through Greenwich, UK.

The International Dateline

The International Dateline is an imaginary line from pole to pole that roughly corresponds to the 180° longitudinal meridian. It is an arbitrary marker between calendar days. The dateline is needed because of the use of local times worldwide rather than a single universal time. Travelers must set their watches back one day when moving from west to east across the dateline. Those traveling in the opposite direction, from east to west, must add a day.

Daylight Saving Time

Daylight saving is a summertime adjustment to the local time in a country or region, designed to cause a higher proportion of citizens’ waking hours to pass during daylight. To follow the system, timepieces are advanced by an hour on a pre-decided date in spring and reverted in the fall. About half of the world’s nations use daylight saving.

Time Zone Map of the World

Click to view a bigger, printable size of the timezone map.

World Time Zones
Map of World Time Zones

Click here for interactive time zone maps and actual time calculator: Timezone maps.

Understanding Time Zones

Click here for interactive Daylight maps.

Time Zones in North America

The following table lists the North American time zone abbreviations.

AbbreviationFull nameOther abbreviationsTime zone
NSTNewfoundland Standard TimeHNTUTC – 3:30 hours
NDTNewfoundland Daylight TimeHATUTC – 2:30 hours
ASTAtlantic Standard TimeHNAUTC – 4 hours
ADTAtlantic Daylight TimeHAAUTC – 3 hours
ESTEastern Standard TimeHNEUTC – 5 hours
EDTEastern Daylight TimeHAEUTC – 4 hours
CSTCentral Standard TimeHNCUTC – 6 hours
CDTCentral Daylight TimeHACUTC – 5 hours
MSTMountain Standard TimeHNRUTC – 7 hours
MDTMountain Daylight TimeHARUTC – 6 hours
PSTPacific Standard TimeHNPUTC – 8 hours
PDTPacific Daylight TimeHAPUTC – 7 hours
AKSTAlaska Standard TimeHNYUTC – 9 hours
AKDTAlaska Daylight TimeHAYUTC – 8 hours
HASTHawaii-Aleutian Standard TimeHSTUTC – 10 hours
HADTHawaii-Aleutian Daylight Time UTC – 9 hours

Time Zones in Australia

The following table lists the Australian time zone abbreviations.

AbbreviationFull nameOther abbreviationsTime zone
NFTNorfolk (Island) Time UTC + 11:30 hours
ESTEastern Standard TimeAESTUTC + 10 hours
EDTEastern Daylight TimeAEDT, ESTUTC + 11 hours
CSTCentral Standard TimeACSTUTC + 9:30 hours
CDTCentral Daylight TimeACDT, CSTUTC + 10:30 hours
WSTWestern Standard TimeAWSTUTC + 8 hours
WDTWestern Daylight TimeAWDT, WSTUTC + 9 hours
CXTChristmas Island Time UTC + 7 hours

Time Zones in Europe

The following table lists the European time zone abbreviations.

The term “IST” is not the legal abbreviation for Irish Summer Time, but it is commonly used. IST is described as “summertime”, according to Irish law, while Irish Standard Time is described as both “standard time” and “winter time”.

AbbreviationFull nameOther abbreviationsTime zone
GMTGreenwich Mean TimeUTCUTC
BSTBritish Summer Time UTC + 1 hour
ISTIrish Summer Time UTC + 1 hour
WETWestern European Time UTC
WESTWestern European Summer TimeWEDTUTC + 1 hour
CETCentral European TimeMEZUTC + 1 hour
CESTCentral European Summer TimeCEDT, MESZUTC + 2 hours
EETEastern European Time UTC + 2 hours
EESTEastern European Summer TimeEEDTUTC + 3 hours
MSKMoscow Standard Time UTC + 3 hours
MSDMoscow Daylight Time UTC + 4 hours

Military / NATO / Letter Time Zones

The following table lists the Military time zone abbreviations.

The basis for this is Z – Zulu time – Zero meridian time – the same as UTC. It’s a convention to assign letters to time zones, where Z= Zero meridian and Zulu is the word that represents the letter Z when it’s used in communication. It is sometimes used in the US military and NATO in conjunction with 24-hour clocks and is popularly used in movies to reference time.

Other letters/words are used for time zones other than UTC, most based on the right or reverse order of the alphabet. Note that ‘J’ is skipped (‘J’ – Juliet refers to the observer’s current local time). There are 25 time zones defined here, but 26 letters in the English Alphabet.

AbbreviationFull nameOther abbreviationsTime zone
ZZulu Time Zone UTC
YYankee Time Zone UTC – 12 hours
XX-ray Time Zone UTC – 11 hours
WWhiskey Time Zone UTC – 10 hours
VVictor Time Zone UTC – 9 hours
UUniform Time Zone UTC – 8 hours
TTango Time Zone UTC – 7 hours
SSierra Time Zone UTC – 6 hours
RRomeo Time Zone UTC – 5 hours
QQuebec Time Zone UTC – 4 hours
PPapa Time Zone UTC – 3 hours
OOscar Time Zone UTC – 2 hours
NNovember Time Zone UTC – 1 hour
AAlpha Time Zone UTC + 1 hour
BBravo Time Zone UTC + 2 hours
CCharlie Time Zone UTC + 3 hours
DDelta Time Zone UTC + 4 hours
EEcho Time Zone UTC + 5 hours
FFoxtrot Time Zone UTC + 6 hours
GGolf Time Zone UTC + 7 hours
HHotel Time Zone UTC + 8 hours
IIndia Time Zone UTC + 9 hours
KKilo Time Zone UTC + 10 hours
LLima Time Zone UTC + 11 hours
MMike Time Zone UTC + 12 hours

Index of Time Zone Acronyms and Abbreviations

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, each of which will also be listed.

AbbreviationFull nameLocationTime zone
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 Daylight. 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 winter is due to the Earth’s axial tilt of 23 degrees. If the Earth were not tilted on its axis, the length of day and night would remain steady year long. During Winter in the northern hemisphere, there are fewer daylight hours, and the southern hemisphere has longer daylight hours and experiences summer.

Daylight Saving Time (called “Summer Time” in many places worldwide) is to make better use of daylight. In Ireland, we advance our clocks forward by one hour in spring to maximize 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 maximize daylight during morning hours.

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