| Africa/Asmera | Africa/Timbuktu | America/Argentina/ComodRivadavia | America/Atka |
| America/Buenos_Aires | America/Catamarca | America/Coral_Harbour | America/Cordoba |
| America/Ensenada | America/Fort_Wayne | America/Indianapolis | America/Jujuy |
| America/Knox_IN | America/Louisville | America/Mendoza | America/Montreal |
| America/Porto_Acre | America/Rosario | America/Santa_Isabel | America/Shiprock |
| America/Virgin | Antarctica/South_Pole | Asia/Ashkhabad | Asia/Calcutta |
| Asia/Chongqing | Asia/Chungking | Asia/Dacca | Asia/Harbin |
| Asia/Istanbul | Asia/Kashgar | Asia/Katmandu | Asia/Macao |
| Asia/Saigon | Asia/Tel_Aviv | Asia/Thimbu | Asia/Ujung_Pandang |
| Asia/Ulan_Bator | Atlantic/Faeroe | Atlantic/Jan_Mayen | Australia/ACT |
| Australia/Canberra | Australia/LHI | Australia/North | Australia/NSW |
| Australia/Queensland | Australia/South | Australia/Tasmania | Australia/Victoria |
| Australia/West | Australia/Yancowinna | Brazil/Acre | Brazil/DeNoronha |
| Brazil/East | Brazil/West | Canada/Atlantic | Canada/Central |
| Canada/East-Saskatchewan | Canada/Eastern | Canada/Mountain | Canada/Newfoundland |
| Canada/Pacific | Canada/Saskatchewan | Canada/Yukon | CET |
| Chile/Continental | Chile/EasterIsland | CST6CDT | Cuba |
| EET | Egypt | Eire | EST |
| EST5EDT | Etc/GMT | Etc/GMT+0 | Etc/GMT+1 |
| Etc/GMT+10 | Etc/GMT+11 | Etc/GMT+12 | Etc/GMT+2 |
| Etc/GMT+3 | Etc/GMT+4 | Etc/GMT+5 | Etc/GMT+6 |
| Etc/GMT+7 | Etc/GMT+8 | Etc/GMT+9 | Etc/GMT-0 |
| Etc/GMT-1 | Etc/GMT-10 | Etc/GMT-11 | Etc/GMT-12 |
| Etc/GMT-13 | Etc/GMT-14 | Etc/GMT-2 | Etc/GMT-3 |
| Etc/GMT-4 | Etc/GMT-5 | Etc/GMT-6 | Etc/GMT-7 |
| Etc/GMT-8 | Etc/GMT-9 | Etc/GMT0 | Etc/Greenwich |
| Etc/UCT | Etc/Universal | Etc/UTC | Etc/Zulu |
| Europe/Belfast | Europe/Nicosia | Europe/Tiraspol | Factory |
| GB | GB-Eire | GMT | GMT+0 |
| GMT-0 | GMT0 | Greenwich | Hongkong |
| HST | Iceland | Iran | Israel |
| Jamaica | Japan | Kwajalein | Libya |
| MET | Mexico/BajaNorte | Mexico/BajaSur | Mexico/General |
| MST | MST7MDT | Navajo | NZ |
| NZ-CHAT | Pacific/Ponape | Pacific/Samoa | Pacific/Truk |
| Pacific/Yap | Poland | Portugal | PRC |
| PST8PDT | ROC | ROK | Singapore |
| Turkey | UCT | Universal | US/Alaska |
| US/Aleutian | US/Arizona | US/Central | US/East-Indiana |
| US/Eastern | US/Hawaii | US/Indiana-Starke | US/Michigan |
| US/Mountain | US/Pacific | US/Pacific-New | US/Samoa |
| UTC | W-SU | WET | Zulu |
Please do not use any of the timezones listed here (besides UTC), they only exist for backward compatible reasons.
If you disregard the above warning, please also note that the IANA timezone database that provides PHP's timezone support uses POSIX style signs, which results in the Etc/GMT+n and Etc/GMT-n time zones being reversed from common usage.
For example, the time zone 8 hours ahead of GMT that is used in China and Western Australia (among other places) is actually Etc/GMT-8 in this database, not Etc/GMT+8 as you would normally expect.
Once again, it is strongly recommended that you use the correct time zone for your location, such as Asia/Shanghai or Australia/Perth for the above examples.
Don’t use 'EST', at least in PHP 5.3.3 it’s the same as 'EST5EDT' rather than being strictly standard time. The only reliable way I’ve found to interpret a time as standard time is to use a UTC-relative format such as:
$dateObject = date_create("2013-06-30 07:00:00-0500");
Take note that while EST and MST are valid, according to this list, PST and CST are not. I am not sure why, but it has caught me off guard. However, if using the DST versions of the "American" timezone strings, you have all four: EST5EDT, CST6CDT, MST7MDT and PST8PDT.
