Less alphabet soup.
Time Zone Abbreviations
Understand common labels, their UTC offsets, and the ambiguities that trip up invitations.
CST and IST are not unique time zones.
CST may mean Central Standard Time in North America or China Standard Time, among other uses. IST can mean India, Irish, or Israel Standard Time. Even familiar labels such as EST describe a fixed offset, while Eastern Time in New York changes with the season. Use a city, full date, and IANA identifier when scheduling.
21 common entries
| Abbreviation | Meaning | UTC offset | Example & caveat |
|---|---|---|---|
| UTC | Coordinated Universal Time | +00:00 | Etc/UTC Fixed reference |
| GMT | Greenwich Mean Time | +00:00 | Europe/London London uses BST in summer |
| EST / EDT | Eastern Standard / Daylight Time | −05:00 / −04:00 | America/New_York Use New York for seasonal rules |
| CST / CDT | Central Standard / Daylight Time (North America) | −06:00 / −05:00 | America/Chicago CST is ambiguous |
| CST | China Standard Time | +08:00 | Asia/Shanghai Also called Beijing time |
| MST / MDT | Mountain Standard / Daylight Time | −07:00 / −06:00 | America/Denver Phoenix generally stays on MST |
| PST / PDT | Pacific Standard / Daylight Time | −08:00 / −07:00 | America/Los_Angeles Use Los Angeles for seasonal rules |
| AKST / AKDT | Alaska Standard / Daylight Time | −09:00 / −08:00 | America/Anchorage Seasonal |
| HST | Hawaii Standard Time | −10:00 | Pacific/Honolulu Honolulu uses this year round |
| BST | British Summer Time | +01:00 | Europe/London BST can also refer to other regions |
| CET / CEST | Central European / Summer Time | +01:00 / +02:00 | Europe/Paris Seasonal |
| EET / EEST | Eastern European / Summer Time | +02:00 / +03:00 | Europe/Helsinki Seasonal |
| IST | India Standard Time | +05:30 | Asia/Kolkata IST is ambiguous |
| IST | Irish Standard Time | +01:00 | Europe/Dublin Summer time in Ireland |
| IST / IDT | Israel Standard / Daylight Time | +02:00 / +03:00 | Asia/Jerusalem Use a city to disambiguate IST |
| JST | Japan Standard Time | +09:00 | Asia/Tokyo Tokyo |
| KST | Korea Standard Time | +09:00 | Asia/Seoul Seoul |
| AWST | Australian Western Standard Time | +08:00 | Australia/Perth Perth |
| ACST / ACDT | Australian Central Standard / Daylight Time | +09:30 / +10:30 | Australia/Adelaide Darwin stays on ACST |
| AEST / AEDT | Australian Eastern Standard / Daylight Time | +10:00 / +11:00 | Australia/Sydney Brisbane stays on AEST |
| NZST / NZDT | New Zealand Standard / Daylight Time | +12:00 / +13:00 | Pacific/Auckland Seasonal |
These are conventional meanings, not a statement that a place uses that offset today. Follow a city link to calculate an exact date, or use the live time-zone directory for labels from our maintained database.