Time Zones of the World

Time Zones

Because Earth is a rotating sphere, the Sun shines on only half of its surface at any one time. Thus, it is simultaneously morning, evening and night time 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.

TimeZone Map
There are 24 one hour time zones around the world, arranged roughly in longitudinal bands.


Geography Lesson Idea - Time Zones

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), but are determined by geographical factors or by 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 standard time varies across those countries. For example, the coterminous United States straddles four time zones and so has four standard times, called the Eastern, Central, Mountain, and Pacific standard times. China is unusual in that 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 around the world rather than a single universal time. When moving from west to east across the dateline, travelers have to set their watches back one day. 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 its 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 back in the fall. About half of the world’s nations use daylight saving.

Time Zone Map of the World

Click to view bigger, printable size of 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

Clich 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 to describe Irish Summer Time but it is commonly used. IST is described as “summer time”, 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 also popular to use in movies to reference time.

Other letters/words are used for other time zones than UTC, most based on the right or reverse order of the Alphabet. Note that 'J' is skipped ('J' - Juliet refers to current local time of the observer). 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, and each of these will be listed as well.

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 Dayl. 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 the winter months is due to Earth’s axial tilt of 23 degrees. If the Earth was not tilted on its axis, the length of day and night would remain steady year long. During winter in the northern hemisphere there are 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.

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