Time Zone Map

Most of the time zones on land are offset from Coordinated Universal Time (UTC) by a whole number of hours (UTC−12:00 to UTC+14:00), but a few zones are offset by 30 or 45 minutes (e.g. Newfoundland Standard Time is UTC−03:30, Nepal Standard Time is UTC+05:45, Indian Standard Time is UTC+05:30 and Myanmar Standard Time is UTC+06:30).

Time Zone Converter

World Clocks

GMT Vancouver San Francisco Seattle
Los Angeles Denver Mexico City Houston
Minneapolis New Orleans Chicago Montgomery
Indianapolis Atlanta Detroit Miami
Washington DC Philadelphia New York Montreal
Boston Buenos Aires Sao Paulo Rio De Janeiro
Lisbon Dublin London Madrid
Barcelona Paris Brussels Amsterdam
Frankfurt Rome Berlin Prague
Vienna Stockholm Athens Helsinki
Minsk Istanbul Cairo Jerusalem
Beirut Moscow Baghdad Dubai
Bangkok Jakarta Hong Kong Beijing
Shanghai Seoul Tokyo Melbourne
Sydney Brisbane Vladivostok Kamchatka

History of Time Zones

When well-regulated mechanical clocks became widespread in the early 19th century, each city began to use local mean solar time. Apparent and mean solar time can differ by up to around 15 minutes (as described by the equation of time) because of the elliptical shape of the Earth's orbit around the Sun (eccentricity) and the tilt of the Earth's axis (obliquity). Mean solar time has days of equal length, and the accumulated difference between the two sums to zero after a year.

Greenwich Mean Time (GMT) was established in 1675, when the Royal Observatory was built, as an aid to mariners to determine longitude at sea, providing a standard reference time while each city in England kept a different local time.

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Local solar time became increasingly inconvenient as rail transport and telecommunications improved, because clocks differed between places by amounts corresponding to the differences in their geographical longitudes, which varied by four minutes of time for every degree of longitude. For example, Bristol, England is about 2.5 degrees west of Greenwich (East London), so when it is solar noon in Bristol, it is about 10 minutes past solar noon in London. The use of time zones accumulates these differences into longer units, usually hours, so that nearby places can share a common standard for timekeeping.

The first adoption of a standard time was in November 1840, in Great Britain by railway companies using GMT kept by portable chronometers. The first of these companies to adopt standard time was the Great Western Railway (GWR) in November 1840. This quickly became known as Railway Time. About August 23, 1852, time signals were first transmitted by telegraph from the Royal Observatory, Greenwich. Even though 98% of Great Britain's public clocks were using GMT by 1855, it was not made Britain's legal time until August 2, 1880. Some British clocks from this period have two minute hands—one for the local time, one for GMT.

Improvements in worldwide communication further increased the need for interacting parties to communicate mutually comprehensible time references to one another. The problem of differing local times could be solved across larger areas by synchronizing clocks worldwide, but in many places that adopted time would then differ markedly from the solar time to which people were accustomed.

On November 2, 1868, the then British colony of New Zealand officially adopted a standard time to be observed throughout the colony, and was the first country to do so. It was based on the longitude 172°30′ East of Greenwich, that is 11 hours 30 minutes ahead of GMT. This standard was known as New Zealand Mean Time.

Timekeeping on the American railroads in the mid-19th century was somewhat confused. Each railroad used its own standard time, usually based on the local time of its headquarters or most important terminus, and the railroad's train schedules were published using its own time. Some junctions served by several railroads had a clock for each railroad, each showing a different time.

Charles F. Dowd proposed a system of one-hour standard time zones for American railroads about 1863, although he published nothing on the matter at that time and did not consult railroad officials until 1869. In 1870 he proposed four ideal time zones (having north–south borders), the first centered on Washington, D.C., but by 1872 the first was centered on the meridian 75° W of Greenwich, with geographic borders (for example, sections of the Appalachian Mountains). Dowd's system was never accepted by American railroads.

Instead, U.S. and Canadian railroads implemented a version proposed by William F. Allen, the editor of the Traveler's Official Railway Guide. The borders of its time zones ran through railroad stations, often in major cities. For example, the border between its Eastern and Central time zones ran through Detroit, Buffalo, Pittsburgh, Atlanta, and Charleston. It was inaugurated on Sunday, November 18, 1883, also called "The Day of Two Noons", when each railroad station clock was reset as standard-time noon was reached within each time zone.

The zones were named Intercolonial, Eastern, Central, Mountain, and Pacific. Within a year 85% of all cities with populations over 10,000, about 200 cities, were using standard time. A notable exception was Detroit (which is about halfway between the meridians of eastern time and central time) which kept local time until 1900, then tried Central Standard Time, local mean time, and Eastern Standard Time before a May 1915 ordinance settled on EST and was ratified by popular vote in August 1916. The confusion of times came to an end when Standard zone time was formally adopted by the U.S. Congress in the Standard Time Act of March 19, 1918.

World Time Zones

The first known person to conceive of a worldwide system of time zones was the Italian mathematician Quirico Filopanti. He introduced the idea in his book Miranda! published in 1858. He proposed 24 hourly time zones, which he called "longitudinal days", the first centered on the meridian of Rome. He also proposed a universal time to be used in astronomy and telegraphy. But his book attracted no attention until long after his death.

Scottish-born Canadian Sir Sandford Fleming proposed a worldwide system of time zones in 1879. He advocated his system at several international conferences, and is credited with "the initial effort that led to the adoption of the present time meridians". In 1876, his first proposal was for a global 24-hour clock, conceptually located at the centre of the Earth and not linked to any surface meridian. In 1879 he specified that his universal day would begin at the anti-meridian of Greenwich (180th meridian), while conceding that hourly time zones might have some limited local use. He also proposed his system at the International Meridian Conference in October 1884, but it did not adopt his time zones because they were not within its purview. The conference did adopt a universal day of 24 hours beginning at Greenwich midnight, but specified that it "shall not interfere with the use of local or standard time where desirable".

By about 1900, almost all inhabited places on Earth had adopted one or other standard time zone; but only some of these used an hourly offset from GMT. Many applied the time at a local astronomical observatory to an entire country, without any reference to GMT. It took many decades before all time zones were based on some "standard offset" from GMT/UTC. By 1929, the majority of countries had adopted hourly time zones, though a number of countries from Iran to Australia had time zones with a 30-minute offset. Nepal was the last country to adopt a standard offset, shifting slightly to UTC+5:45 in 1956.

Today, all nations use standard time zones for secular purposes, but they do not all apply the concept as originally conceived. Newfoundland, India, Iran, Afghanistan, Myanmar, Sri Lanka, the Marquesas, as well as parts of Australia use half-hour deviations from standard time, and some nations, such as Nepal, and some provinces, such as the Chatham Islands of New Zealand, use quarter-hour deviations. Some countries, such as China and India, use a single time zone even though the extent of their territory far exceeds 15° of longitude, which causes problems as some places in China, like Xinjiang (westernmost province of China), uses local time and when planning to meet with the Chinese living in Beijing, a very eastern city, they will have trouble understanding each other as they are two hours apart. Russia is traditionally divided into 11 time zones, but in 2010 the number was reduced to nine. Then-President Dmitry Medvedev said at the time that he would like to see even fewer in place. In 2014, the two removed time zones were reinstated, making the number of time zones 11 again.

France, including its overseas territories, has the most time zones of any country, with a total of 12.

Time Zone UTC Offset UTC DST Offset

UTC & Offsets

If a time is in Coordinated Universal Time (UTC), a "Z" is added directly after the time without a separating space. "Z" is the zone designator for the zero UTC offset. "09:30 UTC" is therefore represented as "09:30Z" or "0930Z". Likewise, "14:45:15 UTC" is written as "14:45:15Z" or "144515Z". UTC time is also known as "Zulu" time, since "Zulu" is a phonetic alphabet code word for the letter "Z".

Offsets from UTC are written in the format ±[hh]:[mm], ±[hh] [mm], or ±[hh] (either hours ahead or behind UTC). For example, if the time being described is one hour ahead of UTC (such as the time in Berlin during the winter), the zone designator would be "+01:00", "+0100", or simply "+01". This numeric representation of time zones is appended to local times in the same way that alphabetic time zone abbreviations (or "Z", as above) are appended. The offset from UTC changes with daylight saving time, e.g. a time offset in Chicago, which is in the North American Central Time Zone, is "−06:00" for the winter (Central Standard Time) and "−05:00" for the summer (Central Daylight Time).

Time Zone Abbreviations

Time zones are often represented by alphabetic abbreviations such as "EST", "WST", and "CST", but these are not part of the international time and date standard ISO 8601 and their use as sole designator for a time zone is discouraged. Such designations can be ambiguous; for example, "CST" can mean China Standard Time (UTC+8), Cuba Standard Time (UTC−5), and (North American) Central Standard Time (UTC−6), and it is also a widely used variant of ACST (Australian Central Standard Time, UTC+9:30).

Such designations predate both ISO 8601 and the internet era; in an earlier era, they were sufficiently unambiguous for many practical uses within a national context (for example, in railway timetables and business correspondence), but their ambiguity explains their deprecation in the internet era, when communications more often cannot rely on implicit geographic context to supply part of the meaning.

Abbreviation Time Zone Offset
ACDT Australian Central Daylight Saving Time UTC+10:30
ACST Australian Central Standard Time UTC+09:30
ACT Acre Time UTC−05
ACT ASEAN Common Time UTC+06:30 – UTC+09
ACWST Australian Central Western Standard Time UTC+08:45
ADT Atlantic Daylight Time UTC−03
AEDT Australian Eastern Daylight Saving Time UTC+11
AEST Australian Eastern Standard Time UTC+10
AET Australian Eastern Time UTC+10/UTC+11
AFT Afghanistan Time UTC+04:30
AKDT Alaska Daylight Time UTC−08
AKST Alaska Standard Time UTC−09
ALMT Alma-Ata Time UTC+06
AMST Amazon Summer Time (Brazil) UTC−03
AMT Amazon Time (Brazil) UTC−04
AMT Armenia Time UTC+04
ANAT Anadyr Time UTC+12
AQTT Aqtobe Time UTC+05
ART Argentina Time UTC−03
AST Arabia Standard Time UTC+03
AST Atlantic Standard Time UTC−04
AWST Australian Western Standard Time UTC+08
AZOST Azores Summer Time UTC±00
AZOT Azores Standard Time UTC−01
AZT Azerbaijan Time UTC+04
BDT Brunei Time UTC+08
BIOT British Indian Ocean Time UTC+06
BIT Baker Island Time UTC−12
BOT Bolivia Time UTC−04
BRST Brasília Summer Time UTC−02
BRT Brasília Time UTC−03
BST Bangladesh Standard Time UTC+06
BST Bougainville Standard Time UTC+11
BST British Summer Time (British Standard Time from Feb 1968 to Oct 1971) UTC+01
BTT Bhutan Time UTC+06
CAT Central Africa Time UTC+02
CCT Cocos Islands Time UTC+06:30
CDT Central Daylight Time (North America) UTC−05
CDT Cuba Daylight Time UTC−04
CEST Central European Summer Time (Cf. HAEC) UTC+02
CET Central European Time UTC+01
CHADT Chatham Daylight Time UTC+13:45
CHAST Chatham Standard Time UTC+12:45
CHOT Choibalsan Standard Time UTC+08
CHOST Choibalsan Summer Time UTC+09
CHST Chamorro Standard Time UTC+10
CHUT Chuuk Time UTC+10
CIST Clipperton Island Standard Time UTC−08
WITA Central Indonesia Time UTC+08
CKT Cook Island Time UTC−10
CLST Chile Summer Time UTC−03
CLT Chile Standard Time UTC−04
COST Colombia Summer Time UTC−04
COT Colombia Time UTC−05
CST Central Standard Time (North America) UTC−06
CST China Standard Time UTC+08
CST Cuba Standard Time UTC−05
CT Central Time UTC−06/UTC−05
CVT Cape Verde Time UTC−01
CWST Central Western Standard Time (Australia) unofficial UTC+08:45
CXT Christmas Island Time UTC+07
DAVT Davis Time UTC+07
DDUT Dumont d'Urville Time UTC+10
DFT AIX-specific equivalent of Central European Time[NB 1] UTC+01
EASST Easter Island Summer Time UTC−05
EAST Easter Island Standard Time UTC−06
EAT East Africa Time UTC+03
ECT Eastern Caribbean Time (does not recognise DST) UTC−04
ECT Ecuador Time UTC−05
EDT Eastern Daylight Time (North America) UTC−04
EEST Eastern European Summer Time UTC+03
EET Eastern European Time UTC+02
EGST Eastern Greenland Summer Time UTC±00
EGT Eastern Greenland Time UTC−01
WIT Eastern Indonesian Time UTC+09
EST Eastern Standard Time (North America) UTC−05
FET Further-eastern European Time UTC+03
FJT Fiji Time UTC+12
FKST Falkland Islands Summer Time UTC−03
FKT Falkland Islands Time UTC−04
FNT Fernando de Noronha Time UTC−02
GALT Galápagos Time UTC−06
GAMT Gambier Islands Time UTC−09
GET Georgia Standard Time UTC+04
GFT French Guiana Time UTC−03
GILT Gilbert Island Time UTC+12
GIT Gambier Island Time UTC−09
GMT Greenwich Mean Time UTC±00
GST South Georgia and the South Sandwich Islands Time UTC−02
GST Gulf Standard Time UTC+04
GYT Guyana Time UTC−04
HDT Hawaii–Aleutian Daylight Time UTC−09
HAEC Heure Avancée d'Europe Centrale French-language name for CEST UTC+02
HST Hawaii–Aleutian Standard Time UTC−10
HKT Hong Kong Time UTC+08
HMT Heard and McDonald Islands Time UTC+05
HOVST Hovd Summer Time (not used from 2017-present) UTC+08
HOVT Hovd Time UTC+07
ICT Indochina Time UTC+07
IDLW International Day Line West time zone UTC−12
IDT Israel Daylight Time UTC+03
IOT Indian Ocean Time UTC+03
IRDT Iran Daylight Time UTC+04:30
IRKT Irkutsk Time UTC+08
IRST Iran Standard Time UTC+03:30
IST Indian Standard Time UTC+05:30
IST Irish Standard Time UTC+01
IST Israel Standard Time UTC+02
JST Japan Standard Time UTC+09
KALT Kaliningrad Time UTC+02
KGT Kyrgyzstan Time UTC+06
KOST Kosrae Time UTC+11
KRAT Krasnoyarsk Time UTC+07
KST Korea Standard Time UTC+09
LHST Lord Howe Standard Time UTC+10:30
LHST Lord Howe Summer Time UTC+11
LINT Line Islands Time UTC+14
MAGT Magadan Time UTC+12
MART Marquesas Islands Time UTC−09:30
MAWT Mawson Station Time UTC+05
MDT Mountain Daylight Time (North America) UTC−06
MET Middle European Time Same zone as CET UTC+01
MEST Middle European Summer Time Same zone as CEST UTC+02
MHT Marshall Islands Time UTC+12
MIST Macquarie Island Station Time UTC+11
MIT Marquesas Islands Time UTC−09:30
MMT Myanmar Standard Time UTC+06:30
MSK Moscow Time UTC+03
MST Malaysia Standard Time UTC+08
MST Mountain Standard Time (North America) UTC−07
MUT Mauritius Time UTC+04
MVT Maldives Time UTC+05
MYT Malaysia Time UTC+08
NCT New Caledonia Time UTC+11
NDT Newfoundland Daylight Time UTC−02:30
NFT Norfolk Island Time UTC+11
NOVT Novosibirsk Time UTC+07
NPT Nepal Time UTC+05:45
NST Newfoundland Standard Time UTC−03:30
NT Newfoundland Time UTC−03:30
NUT Niue Time UTC−11
NZDT New Zealand Daylight Time UTC+13
NZST New Zealand Standard Time UTC+12
OMST Omsk Time UTC+06
ORAT Oral Time UTC+05
PDT Pacific Daylight Time (North America) UTC−07
PET Peru Time UTC−05
PETT Kamchatka Time UTC+12
PGT Papua New Guinea Time UTC+10
PHOT Phoenix Island Time UTC+13
PHT Philippine Time UTC+08
PKT Pakistan Standard Time UTC+05
PMDT Saint Pierre and Miquelon Daylight Time UTC−02
PMST Saint Pierre and Miquelon Standard Time UTC−03
PONT Pohnpei Standard Time UTC+11
PST Pacific Standard Time (North America) UTC−08
PST Philippine Standard Time UTC+08
PYST Paraguay Summer Time UTC−03
PYT Paraguay Time UTC−04
RET Réunion Time UTC+04
ROTT Rothera Research Station Time UTC−03
SAKT Sakhalin Island Time UTC+11
SAMT Samara Time UTC+04
SAST South African Standard Time UTC+02
SBT Solomon Islands Time UTC+11
SCT Seychelles Time UTC+04
SDT Samoa Daylight Time UTC−10
SGT Singapore Time UTC+08
SLST Sri Lanka Standard Time UTC+05:30
SRET Srednekolymsk Time UTC+11
SRT Suriname Time UTC−03
SST Samoa Standard Time UTC−11
SST Singapore Standard Time UTC+08
SYOT Showa Station Time UTC+03
TAHT Tahiti Time UTC−10
THA Thailand Standard Time UTC+07
TFT French Southern and Antarctic Time UTC+05
TJT Tajikistan Time UTC+05
TKT Tokelau Time UTC+13
TLT Timor Leste Time UTC+09
TMT Turkmenistan Time UTC+05
TRT Turkey Time UTC+03
TOT Tonga Time UTC+13
TVT Tuvalu Time UTC+12
ULAST Ulaanbaatar Summer Time UTC+09
ULAT Ulaanbaatar Standard Time UTC+08
UTC Coordinated Universal Time UTC±00
UYST Uruguay Summer Time UTC−02
UYT Uruguay Standard Time UTC−03
UZT Uzbekistan Time UTC+05
VET Venezuelan Standard Time UTC−04
VLAT Vladivostok Time UTC+10
VOLT Volgograd Time UTC+04
VOST Vostok Station Time UTC+06
VUT Vanuatu Time UTC+11
WAKT Wake Island Time UTC+12
WAST West Africa Summer Time UTC+02
WAT West Africa Time UTC+01
WEST Western European Summer Time UTC+01
WET Western European Time UTC±00
WIB Western Indonesian Time UTC+07
WGST West Greenland Summer Time UTC−02
WGT West Greenland Time UTC−03
WST Western Standard Time UTC+08
YAKT Yakutsk Time UTC+09
YEKT Yekaterinburg Time UTC+05
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