Time zones are areas of the Earth that follow the same definition of time. Formerly, people used 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 the Royal Greenwich Observatory in Greenwich, London, England [1]. For this reason the term Greenwich Mean Time (GMT) is still often used (by the BBC, for example, amongst others) to denote the "base time" to which all other time zones are relative. UTC is, nevertheless, the official term for today's atomically measured time as distinct from time determined by astronomical observation as formerly carried out at Greenwich.

GMT (UTC) is, incidentally, local time at Greenwich itself only between 01:00 UTC on the last Sunday in October and 01:00 UTC on the last Sunday in March. For the remainder of the year, as in the rest of Europe, local time is UTC+1 (known in the UK as British Summer Time).

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

• Los Angeles, California, USA: UTC-8 (e.g. if it is 12:00 UTC, then it is 04:00 in Los Angeles)
• New York, New York, USA: UTC-5 (e.g. if it is 11:00 UTC, then it is 06:00 in New York)
• Stockholm, Sweden: UTC+1 (e.g. if it is 12:00 UTC, then it is 13:00 in Stockholm)
• Mumbai, India: UTC+5.5 (e.g. if it is 13:00 UTC, then it is 18:30 in New Dehli)
• Tokyo, Japan: UTC+9 (e.g. if it is 11:00 UTC, then it is 20:00 in Tokyo)

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

• Cairo, Egypt: UTC+2 (e.g. if it is 23:00 UTC on Monday 15 March, then the time in Cairo is 01:00, Tuesday 16 March)
• Auckland, New Zealand: UTC+12 (e.g. if it is 21:00 UTC on Wednesday 30 June, then the time in Auckland is 09:00, 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 03:00 UTC on Saturday 23 July, then the time in Buenos Aires is 23:00, Friday 22 July)
• Honolulu, Hawaii, USA: UTC-10 (e.g. if it is 06:00 UTC on Monday 1 May, then the time in Honolulu is 20:00, 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 18 November 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,

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 - West European Time) 1.15 UTC+1 (CET - Central European Time) 1.16 UTC+2 (EET - East 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 by 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*)
• 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
• 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*
• Puerto Rico
• 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 - West European Time)

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

UTC+1 (CET - Central 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 - East 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 15:00, in the extreme east at 11:00.

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 saving time for each zone and tracks time zones over the years.