Time zone abbreviations are handy but ambiguous. The same letters can mean different places, and many places switch between two abbreviations during the year. Each page below shows the live time with the label that applies today, plus exact change dates.
- UTC: Coordinated Universal Time
- GMT: Greenwich Mean Time
- BST: British Summer Time
- CET and CEST: Central European Time
- EST and EDT: US Eastern Time
- CST and CDT: Central Time
- MST and MDT: Mountain Time
- PST and PDT: Pacific Time
- IST: India Standard Time
- AEST and AEDT: Australian Eastern Time
Common abbreviations at a glance
| Abbreviation | Name | UTC offset | Watch out for |
|---|---|---|---|
| GMT | Greenwich Mean Time | UTC+0 | UK clocks are on BST, not GMT, in summer |
| BST | British Summer Time | UTC+1 | Also Bangladesh Standard Time (UTC+6) |
| IST | India Standard Time | UTC+5:30 | Also Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2) |
| CET / CEST | Central European (Summer) Time | UTC+1 / UTC+2 | Spain's Canary Islands use WET/WEST instead |
| EET / EEST | Eastern European (Summer) Time | UTC+2 / UTC+3 | Used by Finland, Greece, Romania and Ukraine, among others |
| EST / EDT | Eastern Standard / Daylight Time | UTC−5 / UTC−4 | "EST" in summer usually means EDT |
| CST / CDT | Central Standard / Daylight Time | UTC−6 / UTC−5 | CST also means China Standard Time (UTC+8) and Cuba Standard Time (UTC−5) |
| MST / MDT | Mountain Standard / Daylight Time | UTC−7 / UTC−6 | Arizona stays on MST all year |
| PST / PDT | Pacific Standard / Daylight Time | UTC−8 / UTC−7 | PST also means Philippine Standard Time (UTC+8) |
| AEST / AEDT | Australian Eastern Standard / Daylight Time | UTC+10 / UTC+11 | Queensland stays on AEST all year |
| JST | Japan Standard Time | UTC+9 | No daylight saving time |
| SGT | Singapore Time | UTC+8 | No daylight saving time |
| GST | Gulf Standard Time | UTC+4 | Also used for South Georgia Time (UTC−2) |
Why software avoids abbreviations
Computers identify time zones by IANA names such as Europe/London or America/New_York, not by abbreviations. A name like this stands for the full history of a place's rules, so the right offset can be found for any date. The IANA database itself no longer invents abbreviations for places that lack a well-established one. It shows a numeric offset, such as +04, instead, which is why some of our pages show "UTC+4" rather than letters.