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.

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.

Abbreviation	Full name	Other abbreviations	Time zone
NST	Newfoundland Standard Time	HNT	UTC – 3:30 hours
NDT	Newfoundland Daylight Time	HAT	UTC – 2:30 hours
AST	Atlantic Standard Time	HNA	UTC – 4 hours
ADT	Atlantic Daylight Time	HAA	UTC – 3 hours
EST	Eastern Standard Time	HNE	UTC – 5 hours
EDT	Eastern Daylight Time	HAE	UTC – 4 hours
CST	Central Standard Time	HNC	UTC – 6 hours
CDT	Central Daylight Time	HAC	UTC – 5 hours
MST	Mountain Standard Time	HNR	UTC – 7 hours
MDT	Mountain Daylight Time	HAR	UTC – 6 hours
PST	Pacific Standard Time	HNP	UTC – 8 hours
PDT	Pacific Daylight Time	HAP	UTC – 7 hours
AKST	Alaska Standard Time	HNY	UTC – 9 hours
AKDT	Alaska Daylight Time	HAY	UTC – 8 hours
HAST	Hawaii-Aleutian Standard Time	HST	UTC – 10 hours
HADT	Hawaii-Aleutian Daylight Time		UTC – 9 hours

Time Zones in Australia

The following table lists the Australian time zone abbreviations.

Abbreviation	Full name	Other abbreviations	Time zone
NFT	Norfolk (Island) Time		UTC + 11:30 hours
EST	Eastern Standard Time	AEST	UTC + 10 hours
EDT	Eastern Daylight Time	AEDT, EST	UTC + 11 hours
CST	Central Standard Time	ACST	UTC + 9:30 hours
CDT	Central Daylight Time	ACDT, CST	UTC + 10:30 hours
WST	Western Standard Time	AWST	UTC + 8 hours
WDT	Western Daylight Time	AWDT, WST	UTC + 9 hours
CXT	Christmas 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”.

Abbreviation	Full name	Other abbreviations	Time zone
GMT	Greenwich Mean Time	UTC	UTC
BST	British Summer Time		UTC + 1 hour
IST	Irish Summer Time		UTC + 1 hour
WET	Western European Time		UTC
WEST	Western European Summer Time	WEDT	UTC + 1 hour
CET	Central European Time	MEZ	UTC + 1 hour
CEST	Central European Summer Time	CEDT, MESZ	UTC + 2 hours
EET	Eastern European Time		UTC + 2 hours
EEST	Eastern European Summer Time	EEDT	UTC + 3 hours
MSK	Moscow Standard Time		UTC + 3 hours
MSD	Moscow 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.

Abbreviation	Full name	Other abbreviations	Time zone
Z	Zulu Time Zone		UTC
Y	Yankee Time Zone		UTC – 12 hours
X	X-ray Time Zone		UTC – 11 hours
W	Whiskey Time Zone		UTC – 10 hours
V	Victor Time Zone		UTC – 9 hours
U	Uniform Time Zone		UTC – 8 hours
T	Tango Time Zone		UTC – 7 hours
S	Sierra Time Zone		UTC – 6 hours
R	Romeo Time Zone		UTC – 5 hours
Q	Quebec Time Zone		UTC – 4 hours
P	Papa Time Zone		UTC – 3 hours
O	Oscar Time Zone		UTC – 2 hours
N	November Time Zone		UTC – 1 hour
A	Alpha Time Zone		UTC + 1 hour
B	Bravo Time Zone		UTC + 2 hours
C	Charlie Time Zone		UTC + 3 hours
D	Delta Time Zone		UTC + 4 hours
E	Echo Time Zone		UTC + 5 hours
F	Foxtrot Time Zone		UTC + 6 hours
G	Golf Time Zone		UTC + 7 hours
H	Hotel Time Zone		UTC + 8 hours
I	India Time Zone		UTC + 9 hours
K	Kilo Time Zone		UTC + 10 hours
L	Lima Time Zone		UTC + 11 hours
M	Mike 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.

Abbreviation	Full name	Location	Time zone
A	Alpha Time Zone	Military	UTC + 1 hour
ACDT	Australian Central Daylight Time	Australia	UTC + 10:30 hours
ACST	Australian Central Standard Time	Australia	UTC + 9:30 hours
ADT	Atlantic Daylight Time	North America	UTC – 3 hours
AEDT	Australian Eastern Daylight. Time or Australian Eastern Summer Time	Australia	UTC + 11 hours
AEST	Australian Eastern Standard Time	Australia	UTC + 10 hours
AKDT	Alaska Daylight Time	North America	UTC – 8 hours
AKST	Alaska Standard Time	North America	UTC – 9 hours
AST	Atlantic Standard Time	North America	UTC – 4 hours
AWDT	Australian Western Daylight Time	Australia	UTC + 9 hours
AWST	Australian Western Standard Time	Australia	UTC + 8 hours
B	Bravo Time Zone	Military	UTC + 2 hours
BST	British Summer Time	Europe	UTC + 1 hour
C	Charlie Time Zone	Military	UTC + 3 hours
CDT	Central Daylight Time	Australia	UTC + 10:30 hours
CDT	Central Daylight Time	North America	UTC – 5 hours
CEDT	Central European Daylight Time	Europe	UTC + 2 hours
CEST	Central European Summer Time	Europe	UTC + 2 hours
CET	Central European Time	Europe	UTC + 1 hour
CST	Central Summer Time	Australia	UTC + 10:30 hours
CST	Central Standard Time	Australia	UTC + 9:30 hours
CST	Central Standard Time	North America	UTC – 6 hours
CXT	Christmas Island Time	Australia	UTC + 7 hours
D	Delta Time Zone	Military	UTC + 4 hours
E	Echo Time Zone	Military	UTC + 5 hours
EDT	Eastern Daylight Time	Australia	UTC + 11 hours
EDT	Eastern Daylight Time	North America	UTC – 4 hours
EEDT	Eastern European Daylight Time	Europe	UTC + 3 hours
EEST	Eastern European Summer Time	Europe	UTC + 3 hours
EET	Eastern European Time	Europe	UTC + 2 hours
EST	Eastern Summer Time	Australia	UTC + 11 hours
EST	Eastern Standard Time	Australia	UTC + 10 hours
EST	Eastern Standard Time	North America	UTC – 5 hours
F	Foxtrot Time Zone	Military	UTC + 6 hours
G	Golf Time Zone	Military	UTC + 7 hours
GMT	Greenwich Mean Time	Europe	UTC
H	Hotel Time Zone	Military	UTC + 8 hours
HAA	Heure Avancée de l’Atlantique	North America	UTC – 3 hours
HAC	Heure Avancée du Centre	North America	UTC – 5 hours
HADT	Hawaii-Aleutian Daylight Time	North America	UTC – 9 hours
HAE	Heure Avancée de l’Est	North America	UTC – 4 hours
HAP	Heure Avancée du Pacifique	North America	UTC – 7 hours
HAR	Heure Avancée des Rocheuses	North America	UTC – 6 hours
HAST	Hawaii-Aleutian Standard Time	North America	UTC – 10 hours
HAT	Heure Avancée de Terre-Neuve	North America	UTC – 2:30 hours
HAY	Heure Avancée du Yukon	North America	UTC – 8 hours
HNA	Heure Normale de l’Atlantique	North America	UTC – 4 hours
HNC	Heure Normale du Centre	North America	UTC – 6 hours
HNE	Heure Normale de l’Est	North America	UTC – 5 hours
HNP	Heure Normale du Pacifique	North America	UTC – 8 hours
HNR	Heure Normale des Rocheuses	North America	UTC – 7 hours
HNT	Heure Normale de Terre-Neuve	North America	UTC – 3:30 hours
HNY	Heure Normale du Yukon	North America	UTC – 9 hours
I	India Time Zone	Military	UTC + 9 hours
IST	Irish Summer Time	Europe	UTC + 1 hour
K	Kilo Time Zone	Military	UTC + 10 hours
L	Lima Time Zone	Military	UTC + 11 hours
M	Mike Time Zone	Military	UTC + 12 hours
MDT	Mountain Daylight Time	North America	UTC – 6 hours
MESZ	Mitteleuroäische Sommerzeit	Europe	UTC + 2 hours
MEZ	Mitteleuropäische Zeit	Europe	UTC + 1 hour
MSD	Moscow Daylight Time	Europe	UTC + 4 hours
MSK	Moscow Standard Time	Europe	UTC + 3 hours
MST	Mountain Standard Time	North America	UTC – 7 hours
N	November Time Zone	Military	UTC – 1 hour
NDT	Newfoundland Daylight Time	North America	UTC – 2:30 hours
NFT	Norfolk (Island) Time	Australia	UTC + 11:30 hours
NST	Newfoundland Standard Time	North America	UTC – 3:30 hours
O	Oscar Time Zone	Military	UTC – 2 hours
P	Papa Time Zone	Military	UTC – 3 hours
PDT	Pacific Daylight Time	North America	UTC – 7 hours
PST	Pacific Standard Time	North America	UTC – 8 hours
Q	Quebec Time Zone	Military	UTC – 4 hours
R	Romeo Time Zone	Military	UTC – 5 hours
S	Sierra Time Zone	Military	UTC – 6 hours
T	Tango Time Zone	Military	UTC – 7 hours
U	Uniform Time Zone	Military	UTC – 8 hours
UTC	Coordinated Universal Time	Europe	UTC
V	Victor Time Zone	Military	UTC – 9 hours
W	Whiskey Time Zone	Military	UTC – 10 hours
WDT	Western Daylight Time	Australia	UTC + 9 hours
WEDT	Western European Daylight Time	Europe	UTC + 1 hour
WEST	Western European Summer Time	Europe	UTC + 1 hour
WET	Western European Time	Europe	UTC
WST	Western Summer Time	Australia	UTC + 9 hours
WST	Western Standard Time	Australia	UTC + 8 hours
X	X-ray Time Zone	Military	UTC – 11 hours
Y	Yankee Time Zone	Military	UTC – 12 hours
Z	Zulu Time Zone	Military	UTC

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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