Time Zones
Time zones give specific areas on the Earth a time of day that is earlier or later than the neighboring time zones. This is
because when it is day-time on one side of the Earth, it is night-time on the other side. There are 39 time zones dividing
the Earth into different times, each with its own name.
Greenwich Mean Time (GMT) is now called UTC (Coordinated Universal Time). All other parts of the world are offset
(plus or minus) according to their longitude. Most of the zones are offset by a full hour, but there are some offset by half
an hour or 45 minutes.
Time in the United States
Time in the United States is divided into nine standard time zones, with most of the United States observing daylight
saving time for approximately the spring, summer, and fall months.
Daylight saving time (DST) or summer time is the practice of advancing clocks during summer months by one hour so that
in the evening daylight is experienced an hour longer, while sacrificing normal sunrise times. Typically, regions with
summer time adjust clocks forward one hour close to the start of spring and adjust them backward in the autumn to
standard time.
The time zone boundaries and DST observance are regulated by the Department of Transportation. Official and highly
precise timekeeping services (clocks) are provided by two federal agencies: the National Institute of Standards and
Technology (NIST) (an agency of the Department of Commerce); and its military counterpart, the United States Naval
Observatory (USNO). The clocks run by these services are kept synchronized with each other as well as with those of
other international timekeeping organizations.
United States time zones:
Atlantic Time Zone
Eastern Time Zone
Central Time Zone
Mountain Time Zone
Pacific Time Zone
Alaska Time Zone
Hawaii–Aleutian Time Zone
Samoa Time Zone (UTC-11)
Chamorro Time Zone (UTC+10)
From east to west, the times zones of the contiguous United States are:
Eastern Time Zone: (Zone R), which comprises roughly the states on the Atlantic coast and the eastern two thirds of
the Ohio Valley.
Central Time Zone: (Zone S), which comprises roughly the Gulf Coast, Mississippi Valley, and Great Plains.
Mountain Time Zone: (Zone T), which comprises roughly the states that include the Rocky Mountains.
Pacific Time Zone: (Zone U), which comprises roughly the states on the Pacific coast, plus Nevada and the Idaho
panhandle.
Zones used in states beyond the contiguous U.S.
Alaska standard time zone: (AKST; UTC-09; Zone V), which comprises most of the state of Alaska.
Hawaii-Aleutian standard time zone: (or unofficially Hawaii Standard Time: HST) (HAST; UTC-10; zone W), which
includes Hawaii and most of the length of the Aleutian Islands chain (west of 169°30'W).
Zones outside the states
Atlantic standard time zone: (AST; UTC-04; Zone Q), which comprises Puerto Rico and the U.S. Virgin Islands.
Samoa standard time zone (SST; UTC-11; Zone X), which comprises American Samoa.
Chamorro standard time zone: (ChST; UTC+10; Zone K), which comprises Guam and the Northern Mariana
Islands.
| WORLD WIDE TIME ZONE ABBREVIATIONS | ||
|---|---|---|
| ABBREVIATION | TIME ZONE NAME | UTC OFFSET |
| ACDT | AUSTRALIAN CENTRAL DAYLIGHT TIME | UTC + 10:30 |
| ACST | AUSTRALIAN CENTRAL STANDARD TIME | UTC + 9:30 |
| ACWT | AUSTRALIAN CENTRAL WESTERN TIME | UTC + 8:45 |
| ADT | ATLANTIC DAYLIGHT TIME (Caribbean, North America) | UTC - 3 |
| ADT | ARABIA DAYLIGHT TIME | UTC + 3 |
| ACT | ACRE TIME (Brazil) | UTC - 5 |
| AEDT | AUSTRALIAN EASTERN DAYLIGHT TIME | UTC + 11 |
| AEST | AUSTRALIAN EASTERN STANDARD TIME | UTC + 10 |
| AFT | AFGHANISTAN TIME | UTC + 4:30 |
| AKDT | ALASKA DAYLIGHT TIME | UTC - 8 |
| AKST | ALASKA STANDARD TIME | UTC - 9 |
| ALMT | ALMA-ATA TIME | UTC + 6 |
| AMT | ARMENIA TIME | UTC + 4 |
| AMT | AMAZON TIME | UTC - 4 |
| AMST | AMAZON SUMMER TIME | UTC - 3 |
| AMST | ARMENIA SUMMER TIME | UTC + 5 |
| ANAT | ANADYR TIME (Russia) | UTC + 12 |
| ANAST | ANADYR SUMMER TIME (Russia) | UTC + 12 |
| AQTT | AQTOBE TIME (Kazakhstan) | UTC + 5 |
| ART | ARGENTINA TIME | UTC - 3 |
| AST | ATLANTIC STANDARD TIME (Caribbean, North America) | UTC - 4 |
| AST | ARAB STANDARD TIME | UTC + 3 |
| AST | ARABIA STANDARD TIME | UTC + 3 |
| AWDT | AUSTRALIAN WESTERN DAYLIGHT TIME | UTC + 9 |
| AWST | AUSTRALIAN WESTERN STANDARD TIME | UTC + 8 |
| AZOT | AZORES TIME | UTC - 1 |
| AZOST | AZORES SUMMER TIME | UTC + 0 |
| AZT | AZERBAIJAN TIME | UTC + 4 |
| AZST | AZERBAIJAN SUMMER TIME | UTC + 5 |
| BNT | BRUNEI TIME | UTC + 8 |
| BDT | BANGLADESH TIME (also see BST) | UTC + 6 |
| BOT | BOLIVIA TIME | UTC - 4 |
| BRT | BRASILIA TIME | UTC - 3 |
| BRST | BRASILIA SUMMER TIME | UTC - 2 |
| BST | BRITISH SUMMER TIME | UTC + 1 |
| BST | BANGLADESH STANDARD TIME (also see BDT) | UTC + 6 |
| BTT | BHUTAN TIME | UTC + 6 |
| CAST | CASEY TIME (Antarctica) | UTC + 8 |
| CAT | CENTRAL AFRICA TIME | UTC + 2 |
| CCT | COCOS ISLANDS TIME | UTC + 6:30 |
| CDT | CENTRAL DAYLIGHT TIME (Australia) | UTC + 10:30 |
| CDT | CENTRAL DAYLIGHT TIME (North America & Caribbean) | UTC - 5 |
| CEDT | CENTRAL EUROPEAN DAYLIGHT TIME | UTC + 2 |
| CEST | CENTRAL EUROPEAN SUMMER TIME | UTC + 2 |
| CET | CENTRAL EUROPEAN TIME (standard time) | UTC + 1 |
| CHADT | CHATHAM ISLAND DAYLIGHT TIME | UTC + 13:45 |
| CHAST | CHATHAM ISLAND STANDARD TIME | UTC + 12:45 |
| CHOT | CHOIBALSAN TIME (Mongolia) | UTC + 8 |
| CHOST | CHOIBALSAN SUMMER TIME (Mongolia) | UTC + 9 |
| CHsT | CHAMORRO STANDARD TIME | UTC + 10 |
| CHUT | CHUUK TIME | UTC + 10 |
| CIT | CENTRAL INDONESIAN TIME (see abbreviation WITA) | UTC + 8 |
| CKT | COOK ISLAND TIME | UTC - 10 |
| CLST | CHILE SUMMER TIME | UTC - 3 |
| CLT | CHILE STANDARD TIME | UTC - 4 |
| COT | COLUMBIA TIME | UTC - 5 |
| CST | CENTRAL STANDARD TIME (Australia) | UTC + 9:30 |
| CST | CENTRAL STANDARD TIME (North America & Central America) | UTC - 6 |
| CST | CUBA STANDARD TIME | UTC - 5 |
| CST | CHINA STANDARD TIME | UTC + 8 |
| CVT | CAPE VERDE TIME | UTC - 1 |
| CWST | CENTRAL WESTERN AUSTRALIA TIME (Eucla) | UTC + 8:45 |
| CXT | CHRISTMAS ISLAND TIME | UTC + 7 |
| DAVT | DAVIS TIME (Antarctica) | UTC + 7 |
| DDUT | DUMONT D 'URVILLE TIME | UTC + 10 |
| DST | DAYLIGHT SAVING TIME | VARIES |
| EASST | EASTERN ISLAND SUMMER TIME | UTC - 5 |
| EAST | EASTERN ISLAND STANDARD TIME | UTC - 6 |
| EAT | EAST AFRICA TIME | UTC + 3 |
| ECT | ECUADOR TIME | UTC - 5 |
| EDT | EASTERN DAYLIGHT TIME (Australia and Pacific) | UTC + 11 |
| EDT | EASTERN DAYLIGHT TIME (North America and Caribbean) | UTC - 4 |
| EEDT | EASTERN EUROPEAN DAYLIGHT TIME | UTC + 3 |
| EEST | EASTERN EUROPEAN SUMMER TIME | UTC + 3 |
| EET | EASTERN EUROPEAN TIME | UTC + 2 |
| EGT | EASTERN GREENLAND TIME | UTC - 1 |
| EGST | EASTERN GREENLAND SUMMER TIME | UTC + 0 |
| EST | EASTERN STANDARD TIME (Australia and Pacific) | UTC + 10 |
| EST | EASTERN STANDARD TIME (North America and Caribbean) | UTC - 5 |
| EIT | EASTERN INDONESIAN TIME (see WIT) | UTC + 9 |
| FET | FURTHER-EASTERN EUROPEAN TIME | UTC + 3 |
| FJT | FIJI TIME | UTC + 12 |
| FJST | FIJI SUMMER TIME | UTC + 13 |
| FKST | FALKLAND ISLANDS SUMMER TIME | UTC - 3 |
| FKT | FALKLAND ISLANDS TIME | UTC - 4 |
| FNT | FERNANDO de NORONHA | UTC - 2 |
| GALT | GALAPAGOS TIME | UTC - 6 |
| GAMT | GAMBIER TIME | UTC - 9 |
| GET | GEORGIA STANDARD TIME | UTC + 4 |
| GFT | FRENCH GUIANA TIME | UTC - 3 |
| GILT | GILBERT ISLAND TIME | UTC + 12 |
| GMT | GREENWICH MEAN TIME | UTC + 0 |
| GST | GULF STANDARD TIME | UTC + 4 |
| GST | SOUTH GEORGIA TIME (South Georgia and the South Sandwich Islands) | UTC - 2 |
| GYT | GUYANA TIME | UTC - 4 |
| HADT | HAWAII-ALEUTIAN DAYLIGHT TIME | UTC - 9 |
| HAST | HAWAII-ALEUTIAN STANDARD TIME | UTC - 10 |
| HKT | HONG KONG TIME | UTC + 8 |
| HOVT | HOVD TIME (Mongolia) | UTC + 7 |
| HOVST | HOVD SUMMER TIME (Mongolia) | UTC + 8 |
| HST | HAWAII STANDARD TIME | UTC - 10 |
| ICT | INDOCHINA TIME | UTC + 7 |
| IDT | ISRAEL DAYLIGHT TIME | UTC + 3 |
| IOT | INDIAN CHAGOS TIME (British Indian Ocean Territory) | UTC + 6 |
| IRDT | IRAN DAYLIGHT TIME | UTC + 4:30 |
| IRKT | IRKUTSK TIME | UTC + 8 |
| IRKST | IRKUTSK SUMMER TIME | UTC + 9 |
| IRST | IRAN STANDARD TIME | UTC + 3:30 |
| IST | INDIAN STANDARD TIME | UTC + 5:30 |
| IST | ISRAEL STANDARD TIME | UTC + 2 |
| IST | IRISH STANDARD TIME (IST is used during daylight saving time) | UTC + 1 |
| JST | JAPAN STANDARD TIME | UTC + 9 |
| KGT | KYRGYZSTAN TIME | UTC + 6 |
| KOST | KOSRAE TIME (Micronesia) | UTC + 11 |
| KRAT | KRASNOYARSK TIME | UTC + 7 |
| KRAST | KRASNOYARSK SUMMER TIME | UTC + 8 |
| KST | KOREA STANDARD TIME | UTC + 9 |
| KUYT | KUYBYSHEV TIME (Samara Time as of 1991) | UTC + 4 |
| LHDT | LORD HOWE DAYLIGHT TIME | UTC + 11 |
| LHST | LORD HOWE STANDARD TIME | UTC + 10:30 |
| LINT | LINE ISLANDS TIME | UTC + 14 |
| MAGT | MAGADAN TIME | UTC + 10 |
| MAGST | MAGADAN SUMMER TIME | UTC + 12 |
| MART | MARQUESAS TIME | UTC - 9:30 |
| MAWT | MAWSON STATION TIME (Antarctic) | UTC + 5 |
| MDT | MOUNTAIN DAYLIGHT TIME (North America) | UTC - 6 |
| MeST | METLAKATLA (Alaska Indian Community) | UTC - 8 |
| MHT | MARSHALL ISLANDS TIME | UTC + 12 |
| MIST | MACQUARIE ISLAND STATION TIME | UTC + 11 |
| MMT | MYANMAR TIME | UTC + 6:30 |
| MSD | MOSCOW SUMMER TIME | UTC + 4 |
| MSK | MOSCOW STANDARD TIME | UTC + 3 |
| MST | MOUNTAIN STANDARD TIME (North America) | UTC - 7 |
| MUT | MAURITIUS TIME | UTC + 4 |
| MVT | MALDIVES TIME | UTC + 5 |
| MYT | MALAYSIA TIME | UTC + 8 |
| NCT | NEW CALEDONIA TIME | UTC + 11 |
| NDT | NEWFOUNDLAND DAYLIGHT TIME | UTC - 2:30 |
| NFT | NORFOLK TIME | UTC + 11:30 |
| NOVT | NOVOSIBIRSK TIME | UTC + 6 |
| NOVST | NOVOSIBIRSK SUMMER TIME | UTC + 7 |
| NPT | NEPAL TIME | UTC + 5:45 |
| NRT | NAURU TIME | UTC + 12 |
| NST | NEWFOUNDLAND STANDARD TIME | UTC - 3:30 |
| NT | NEWFOUNDLAND TIME | UTC - 3:30 |
| NUT | NIUE TIME | UTC - 11 |
| NZDT | NEW ZEALAND DAYLIGHT TIME | UTC + 13 |
| NZST | NEW ZEALAND STANDARD TIME | UTC + 12 |
| OMST | OMSK STANDARD TIME | UTC + 6 |
| OMSST | OMSK SUMMER TIME | UTC + 7 |
| ORAT | ORAL TIME | UTC + 5 |
| PDT | PACIFIC DAYLIGHT TIME (North America) | UTC - 7 |
| PET | PERU TIME | UTC - 5 |
| PETT | KAMCHATKA TIME | UTC + 12 |
| PETST | KAMCHATKA SUMMER TIME | UTC + 12 |
| PGT | PAPUA NEW GUINEA TIME | UTC + 10 |
| PHT | PHILIPPINE TIME | UTC + 8 |
| PHOT | PHOENIX ISLAND TIME | UTC + 13 |
| PKT | PAKISTAN STANDARD TIME | UTC + 5 |
| PMDT | PIERRE & MIQUELON DAYLIGHT TIME | UTC - 2 |
| PMST | PIERRE & MIQUELON STANDARD TIME | UTC - 3 |
| PONT | POHNPEI TIME (Formerly Ponape) | UTC+ 11 |
| PST | PACIFIC STANDARD TIME (North America) | UTC - 8 |
| PST | PITCAIRN TIME | UTC - 8 |
| PST | PYONGYANG TIME (North Korea) | UTC + 8:30 |
| PWT | PALAU TIME | UTC + 9 |
| PYT | PARAGUAY TIME | UTC - 4 |
| PYST | PARAGUAY SUMMER TIME | UTC - 3 |
| QYZT | QYZYLORDA TIME (Kazakhstan) | UTC +6 |
| RET | REUNION TIME | UTC + 4 |
| ROTT | ROTHERA (RESEARCH STATION) TIME (Antarctica) | UTC - 3 |
| SAKT | SAKHALIN TIME | UTC + 10 |
| SAKST | SAKHALIN SUMMER TIME | UTC + 12 |
| SAMT | SAMARA TIME | UTC + 4 |
| SAST | SOUTH AFRICA STANDARD TIME | UTC + 2 |
| SBT | SOLOMON ISLANDS TIME | UTC + 11 |
| SCT | SEYCHELLES TIME | UTC + 4 |
| SGT | SINGAPORE TIME | UTC + 8 |
| SRT | SURINAME TIME | UTC - 3 |
| SLT | SRI LANKA TIME | UTC + 5:30 |
| SLST | SRI LANKA TIME | UTC + 5:30 |
| SRET | SREDNEKOLYMSK TIME | UTC + 11 |
| SST | SAMOA STANDARD TIME (American Samoa) | UTC - 11 |
| SYOT | SYOWA (RESEARCH STATION) TIME (Antarctica) | UTC + 3 |
| TAHT | TAHITI TIME | UTC - 10 |
| TFT | FRENCH SOUTHERN AND ANTARCTIC TERRITORIES TIME | UTC + 5 |
| TJT | TAJIKISTAN TIME | UTC + 5 |
| TKT | TOKELAU TIME | UTC + 13 |
| TLT | EAST TIMOR TIME (Timor-Leste Time) | UTC + 9 |
| TMT | TURKMENISTAN TIME | UTC + 5 |
| TOT | TONGA TIME | UTC + 13 |
| TRUT | TRUK TIME (Micronesia) | UTC + 10 |
| TVT | TUVALU TIME | UTC + 12 |
| ULAT | ULAANBAATAR TIME | UTC + 8 |
| ULAST | ULAANBAATAR SUMMER TIME | UTC + 9 |
| UTC | COORDINATED UNIVERSAL TIME | UTC + 0 |
| UYST | URUGUAY SUMMER TIME | UTC - 2 |
| UYT | URUGUAY STANDARD TIME | UTC - 3 |
| UZT | UZBEKISTAN TIME | UTC + 5 |
| VET | VENEZUELAN STANDARD TIME | UTC - 4:30 |
| VLAT | VLADIVOSTOK TIME | UTC + 10 |
| VLAST | VLADIVOSTOK SUMMER TIME | UTC + 11 |
| VOLT | VOLGOGRAD TIME | UTC + 4 |
| VUT | VANUATU TIME | UTC + 11 |
| WAKT | WAKE ISLAND TIME | UTC + 12 |
| WAT | WEST AFRICA TIME | UTC + 1 |
| WART | WEST ARGENTINA TIME | UTC - 4 |
| WAST | WEST AFRICA SUMMER TIME | UTC + 2 |
| WDT | WESTERN DAYLIGHT TIME (Australia) | UTC + 9 |
| WEDT | WESTERN EUROPEAN DAYLIGHT TIME | UTC + 1 |
| WEST | WESTERN EUROPEAN SUMMER TIME | UTC + 1 |
| WET | WESTERN EUROPEAN TIME | UTC + 0 |
| WFT | WALLIS AND FUTUNA TIME | UTC + 12 |
| WGT | WESTERN GREENLAND TIME | UTC - 3 |
| WGST | WESTERN GREENLAND SUMMER TIME | UTC - 2 |
| WIB | WESTERN INDONESIAN TIME | UTC + 7 |
| WIT | EASTERN INDONESIAN TIME | UTC + 9 |
| WITA | CENTRAL INDONESIAN TIME | UTC + 8 |
| WST | WESTERN SAHARA SUMMER TIME | UTC + 1 |
| WST | WESTERN STANDARD TIME (Australia) | UTC + 8 |
| WST | WESTERN SAMOA TIME (standard time) | UTC + 13 |
| WST | WESTERN SAMOA TIME (*also used during daylight saving time) | UTC + 14 |
| WT | WESTERN SAHARA STANDARD TIME | UTC + 0 |
| YAKT | YAKUTSK TIME | UTC + 9 |
| YAKST | YAKUTSK SUMMER TIME | UTC + 10 |
| YAP | YAP TIME (Micronesia) | UTC + 10 |
| YEKT | YEKATERINBURG TIME | UTC + 5 |
| YEKST | YEKATERINBURG SUMMER TIME | UTC + 6 |