Time zone

Time zones are areas of the Earth that follow the same definition of time. Formerly, people were using apparent solar time, resulting in the time differing slightly from town to town. Time zones partially rectified the problem by setting the clocks of a region to the same mean solar time. Time zones are generally centered on meridians of a longitude that is a multiple of 15º; however as the map below shows, the shapes of time zones can be quite irregular because of boundaries of countries.

All time zones are defined relative to Coordinated Universal Time (UTC). The reference point for Time Zones is the Prime Meridian (longitude 000) which passes through inside the Royal Greenwich Observatory in Greenwich, London, England [1]. The reference time was originally called Greenwich Mean Time (GMT), but is now referred to as Coordinated Universal Time (UTC) to distinguish it from the local time in London which may be adjusted for daylight saving time.

The time for a location is given relative to UTC. Some examples:

• Los Angeles, California, USA: UTC-8 (e.g. if it is 12noon UTC, then it is 4am in Los Angeles)
• New York, New York, USA: UTC-5 (e.g. if it is 11am UTC, then it is 6am in New York)
• Stockholm, Sweden: UTC+1 (e.g. if it is 12noon UTC, then it is 1pm in Stockholm)
• Mumbai, India: UTC+5 (e.g. if it is 1pm UTC, then it is 5pm in New Dehli)
• Tokyo, Japan: UTC+9 (e.g. if it is 11am UTC, then it is 8pm in Tokyo)

Where the adjustment for time zones results in a time after 12midnight, then the date at the location is one day later. Some examples:

• Cairo, Egypt: UTC+2 (e.g. if it is 11pm UTC on Monday 15 March, then the time in Cairo is 1 am, Tuesday 16 March)
• Auckland, New Zealand: UTC+12 (e.g. if it is 9pm UTC on Wednesday 30 June, then the time in Auckland is 9 am, Thursday 1 July)

Where the adjustment for time zones results in a time before 00:00 (i.e. midnight), then the date at the location is one day earlier. Some examples:

• Buenos Aires, Argentina: UTC-4 (e.g. if it is 3am UTC on Saturday 23 July, then the time in Buenos Aires is 11 pm, Friday 22 July)
• Honolulu, Hawaii, USA: UTC-10 (e.g. if it is 6am UTC on Monday 1 May, then the time in Honolulu is 8 pm, Sunday 30 April)

Note: The time zone adjustment for a specific location may vary due to the use of daylight saving time.

• e.g. New Zealand which is usually UTC+12, observes a one hour daylight saving time adjustment during the southern hemisphere summer resulting in a local time of UTC+13!

Time zones were invented by Sanford Fleming because of the need of railroad companies to have consistent local times between railroad stations. [1] On November 18, 1883, railroads in the United States and Canada became the first to institute time zones when they established four standard continental time zones in North America. This ended a great deal of confusion created by previously having thousands of local times. Worldwide adoption of time zones followed the next year.

See also: Sidereal time Calculating local time

A map of the world's time zones, Larger image

Table of contents

1 List of time zones and contained areas 1.1 UTC-11 (BEST - Bering Standard Time) 1.2 UTC-10 (HST - Hawaii-Aleutian Standard Time) 1.3 UTC-9:30 1.4 UTC-9 (AKST - Alaska Standard Time) 1.5 UTC-8 (PST - Pacific Standard Time) 1.6 UTC-7 (MST - Mountain Standard Time) 1.7 UTC-6 (CST - Central Standard Time) 1.8 UTC-5 (EST - Eastern Standard Time) 1.9 UTC-4 (AST - Atlantic Standard Time) 1.10 UTC-3:30 (NST - Newfoundland Standard Time) 1.11 UTC-3 1.12 UTC-2 1.13 UTC-1 1.14 UTC (WET - Western European Time, also called GMT) 1.15 UTC+1 (CET - Central European Time, also called MET - Middle European Time) 1.16 UTC+2 (EET - Eastern European Time) 1.17 UTC+3 (MSK - Moscow Time) 1.18 UTC+3:30 1.19 UTC+4 1.20 UTC+4:30 1.21 UTC+5 1.22 UTC+5:30 1.23 UTC+5:45 1.24 UTC+6 1.25 UTC+6:30 1.26 UTC+7 1.27 UTC+8 (AWST - Australian Western Standard Time) 1.28 UTC+9 1.29 UTC+9:30 (ACST - Australian Central Standard Time) 1.30 UTC+10 (AEST - Australian Eastern Standard Time) 1.31 UTC+10:30 1.32 UTC+11 1.33 UTC+11:30 1.34 UTC+12 1.35 UTC+12:45 1.36 UTC+13 1.37 UTC+14 2 External links

List of time zones and contained areas

Regions with * observe Daylight Saving Time: add 1 hour in summer.

Note that some regions differ 24 hours in time: they have the same time of the day but differ a full day. The two extreme time zones even differ 25 hours, hence during one hour a day the date differs 2 days.

UTC-11 (BEST - Bering Standard Time)

• American Samoa
• Midway Islands
• Niue
• Samoa

UTC-10 (HST - Hawaii-Aleutian Standard Time)

• French Polynesia (Society Archipelago including Tahiti, Tuamotu Archipelago, Tubuai Islands)
• Johnston Atoll
• United States (Hawaii)
• United States (Aleutian Islands of Alaska)*

UTC-9:30

• French Polynesia (Marquesas Islands)

UTC-9 (AKST - Alaska Standard Time)

• French Polynesia (Gambier Islands)
• United States (Alaska*)

UTC-8 (PST - Pacific Standard Time)

• Canada (British Columbia*, Yukon*)
• Mexico (Baja California Norte*)
• United States (California*, Idaho (northern)*, Nevada*, Oregon (except Malheur County)*, Washington*

UTC-7 (MST - Mountain Standard Time)

• Canada (Alberta*, Northwest Territories*, Nunavut (Mountain)*)
• Mexico (Baja California Sur*, Chihuahua*, Nayarit*, Sinaloa*, Sonora)
• United States (Arizona (Navajo Nation does observe DST), Colorado*, Idaho (southern)*, Montana*, Nebraska (western)*, New Mexico*, North Dakota (western)*, Oregon (Malheur County)* South Dakota (western)*, Utah*, Wyoming*)

UTC-6 (CST - Central Standard Time)

• Belize
• Canada (Manitoba*, Nunavut (Southampton Island), Nunavut (Central)*, Ontario (Western)*, Saskatchewan)
• Chile (Easter Island)
• Costa Rica
• Ecuador (Galapagos Islands)
• El Salvador
• Guatemala
• Honduras
• Mexico* (all other states not already mentioned, plus Distrito Federal)
• Nicaragua
• Puerto Rico
• United States (Alabama*, Arkansas*, Illinois*, Indiana* (northwest and southwest), Iowa*, Kansas*, Kentucky (western)*, Louisiana*, Minnesota*, Mississippi*, Missouri*, Nebraska (eastern)*, North Dakota*, Oklahoma*, South Dakota (eastern)*, Tennessee (middle and western)*, Texas*, Wisconsin*)

UTC-5 (EST - Eastern Standard Time)

• Brazil (Acre)
• Canada (Nunavut (Eastern)*, Ontario*, Quebec*)
• Cayman Islands
• Colombia
• Cuba*
• Ecuador
• Haiti
• Jamaica
• Panama
• Peru
• Turks and Caicos Islands*
• United States (Connecticut*, Delaware*, District of Columbia*, Florida*, Georgia*, Indiana (most of state), Kentucky (eastern and central)*, Maine*, Maryland*, Massachusetts*, Michigan*, New Hampshire*, New Jersey*, New York*, North Carolina*, Ohio*, Pennsylvania*, Rhode Island*, South Carolina*, Tennessee (eastern)*, Vermont*, Virginia*, West Virginia*)

UTC-4 (AST - Atlantic Standard Time)

• Anguilla
• Antigua and Barbuda
• Aruba
• Barbados
• Bolivia
• Brazil (Amazonas, Mato Grosso*, Mato Grosso do Sul*, Para (western), Rondonia, Roraima)
• Canada (Labrador*, New Brunswick*, Nova Scotia*, Prince Edward Island*)
• Chile*
• Dominica
• Dominican Republic
• Falkland Islands*
• Grenada
• Guadeloupe
• Guyana
• Martinique
• Montserrat
• Netherlands Antilles
• Paraguay*
• Saint Kitts and Nevis
• Saint Lucia
• Saint Vincent and the Grenadines
• Trinidad and Tobago
• Venezuela
• Virgin Islands

UTC-3:30 (NST - Newfoundland Standard Time)

• Canada (Newfoundland*)

UTC-3

• Argentina
• Bahamas*
• Brazil (Alagoas, Amapa, Bahia*, Ceara, Distrito Federal*, Espirito Santo*, Goias*, Maranhao, Minas Gerais*, Para (eastern), Paraiba, Parana*, Pernambuco, Piaui, Rio de Janeiro*, Rio Grande do Norte, Rio Grande do Sul*, Santa Catarina*, Sao Paulo*, Sergipe, Tocantins*)
• French Guiana*
• Greenland
• Saint Pierre and Miquelon*
• Suriname
• Uruguay

UTC-2

• Bermuda*
• Brazil (Fernando de Noronha)

UTC-1

• Cape Verde
• Portugal (Azores*)

UTC (WET - Western European Time, also called GMT)

• Burkina Faso
• Côte d'Ivoire
• Faroe Islands*
• The Gambia
• Ghana
• Guinea
• Guinea-Bissau
• Iceland
• Ireland*
• Liberia
• Mali
• Mauritania
• Morocco
• Portugal*
• Saint Helena
• Sao Tome and Principe
• Senegal
• Sierra Leone
• Spain* (Canary Islands)
• Togo
• United Kingdom*

UTC+1 (CET - Central European Time, also called MET - Middle European Time)

• Albania*
• Andorra*
• Angola
• Austria*
• Belgium*
• Benin
• Bosnia and Herzegovina*
• Cameroon
• Central African Republic
• Chad
• Congo, Republic of the
• Congo, Democratic Republic of the (Kinshasa, Bandungu, Bas-Zaire, Equateur)
• Croatia*
• Czech Republic*
• Denmark*
• Equatorial Guinea
• Republic of Macedonia*
• France*
• Gabon
• Germany*
• Gibraltar*
• Hungary*
• Italy*
• Liechtenstein*
• Luxembourg*
• Malta*
• Monaco*
• Montenegro*
• Namibia*
• Netherlands*
• Niger
• Nigeria
• Norway*
• Poland*
• San Marino*
• Serbia*
• Slovakia*
• Slovenia*
• Spain*
• Svalbard and Jan Mayen*
• Sweden*
• Switzerland*
• Tunisia

UTC+2 (EET - Eastern European Time)

• Belarus*
• Botswana
• Bulgaria*
• Burundi
• Congo, Democratic Republic of the (Kasai Occidental, Kasai Oriental, Haut-Zaire, Shaba)
• Cyprus*
• Egypt*
• Estonia
• Finland*
• Gaza Strip*
• Greece*
• Israel*
• Jordan
• Latvia*
• Lebanon*
• Lesotho
• Libya
• Lithuania
• Malawi
• Moldova*
• Mozambique
• Romania*
• Russia (Zone 1*, including Kalingrad)
• Rwanda
• South Africa
• Swaziland
• Syria*
• Turkey*
• Ukraine*
• West Bank*
• Zambia
• Zimbabwe

UTC+3 (MSK - Moscow Time)

• Bahrain
• Comoros
• Djibouti
• Eritrea
• Ethiopia
• Iraq*
• Kenya
• Kuwait
• Madagascar
• Mayotte
• Qatar
• Russia (Zone 2*, including Moscow and St. Petersburg; this time zone applies also for railways throughout Russia)
• Saudi Arabia
• Somalia
• Sudan
• Tanzania
• Uganda
• Yemen

UTC+3:30

• Iran*

UTC+4

• Georgia*
• Kazakhstan (Western)*
• Mauritius
• Oman
• Reunion
• Russia (Zone 3*)
• Seychelles
• United Arab Emirates

UTC+4:30

• Afghanistan

UTC+5

• Armenia
• Azerbaijan*
• Kazakhstan (Central)*
• Kyrgyzstan*
• Maldives
• Pakistan
• Russia (Zone 4*, including Ekaterinburg and Perm)
• Tajikistan
• Turkmenistan
• Uzbekistan

UTC+5:30

• India

UTC+5:45

• Nepal

UTC+6

• Bangladesh
• Bhutan
• Kazakhstan (Eastern)*
• Russia (Zone 5*, including Novosibirsk and Omsk)
• Sri Lanka

UTC+6:30

• Cocos Islands
• Myanmar

UTC+7

• Cambodia
• Christmas Island (Australia)
• Indonesia (Western)
• Laos
• Russia (Zone 6*)
• Thailand
• Vietnam

UTC+8 (AWST - Australian Western Standard Time)

• Australia (Western Australia)
• Brunei
• Mainland China
• Hong Kong
• Indonesia (Central)
• Macau
• Malaysia
• Mongolia
• Philippines
• Russia (Zone 7*)
• Singapore
• Taiwan

Note that the whole of China has the same time, which makes this time zone exceptionally wide. In the extreme west of China the sun is at its highest at 3 pm, in the extreme east at 11 am.

UTC+9

• East Timor
• Indonesia (Eastern)
• Japan (JST - Japan Standard Time)
• North Korea
• South Korea
• Palau
• Russia (Zone 8*, including Yakutsk)

UTC+9:30 (ACST - Australian Central Standard Time)

• Australia (Broken Hill, NSW; Northern Territory; South Australia*)

UTC+10 (AEST - Australian Eastern Standard Time)

• Australia (Australian Capital Territory*, New South Wales* (except Broken Hill, which observes South Australia time), Queensland, Victoria*, Tasmania*)
• Cook Islands
• Guam
• Federated States of Micronesia (Yap and Chuuk)
• Northern Mariana Islands
• Papua New Guinea
• Russia (Zone 9*, including Vladivostok)

UTC+10:30

• Australia (Lord Howe Island*)(DST only 0:30)

UTC+11

• Federated States of Micronesia (Kosrae and Pohnpei)
• New Caledonia
• Russia (Zone 10*)
• Solomon Islands
• Vanuatu

UTC+11:30

• Norfolk Island

UTC+12

• Fiji*
• Kiribati (Gilbert Islands)
• Marshall Islands
• Nauru
• New Zealand (Aotearoa)*
• Russia (Zone 11*)
• Tuvalu
• Wake Island
• Wallis and Futuna

UTC+12:45

• New Zealand (Aotearoa) (Chatham Islands*)

UTC+13

• Kiribati (Phoenix Islands)
• Tonga

UTC+14

• Kiribati (Line Islands)

External links

• World Time Server
• A Solution for Managing Time Zones, and Dates in International Internet Systems
• The tz database provides specific information on the beginning and ending dates of daylight savings time for each zone and tracks time zones over the years.