Reference guide
Abbreviations can be ambiguousTime Zone Abbreviations
Look up common time-zone abbreviations, typical offsets and ambiguity notes before using them in a conversion.
| Abbreviation | Typical offset | Common meaning | Scope note |
|---|---|---|---|
| UTC | UTC+00:00 | Coordinated Universal Time | Generally unambiguous |
| GMT | UTC+00:00 | Greenwich Mean Time | Often used as a zero-offset reference |
| EST | UTC−05:00 | Eastern Standard Time | North America standard-time usage |
| EDT | UTC−04:00 | Eastern Daylight Time | North America daylight-time usage |
| CST | UTC−06:00 / UTC+08:00 | Central Standard Time / China Standard Time | Ambiguous |
| CDT | UTC−05:00 | Central Daylight Time | North America daylight-time usage |
| MST | UTC−07:00 | Mountain Standard Time | Can be seasonal or fixed depending on place |
| MDT | UTC−06:00 | Mountain Daylight Time | North America daylight-time usage |
| PST | UTC−08:00 | Pacific Standard Time | North America standard-time usage |
| PDT | UTC−07:00 | Pacific Daylight Time | North America daylight-time usage |
| CET | UTC+01:00 | Central European Time | Seasonal pair with CEST in many countries |
| CEST | UTC+02:00 | Central European Summer Time | Daylight-time usage |
| EET | UTC+02:00 | Eastern European Time | Seasonal in many countries |
| EEST | UTC+03:00 | Eastern European Summer Time | Daylight-time usage |
| BST | UTC+01:00 / other | British Summer Time | Ambiguous globally |
| IST | UTC+05:30 / UTC+01:00 / UTC+02:00 | India / Irish Summer / Israel Standard | Highly ambiguous |
| AST | UTC−04:00 / UTC+03:00 | Atlantic Standard / Arabia Standard | Ambiguous |
| JST | UTC+09:00 | Japan Standard Time | No seasonal clock change |
| KST | UTC+09:00 | Korea Standard Time | No seasonal clock change |
| MYT | UTC+08:00 | Malaysia Time | No seasonal clock change |
| SGT | UTC+08:00 | Singapore Time | No seasonal clock change |
| HKT | UTC+08:00 | Hong Kong Time | No seasonal clock change |
| ICT | UTC+07:00 | Indochina Time | Used in parts of Southeast Asia |
| AEST | UTC+10:00 | Australian Eastern Standard Time | Some regions switch to AEDT; Queensland does not |
| AEDT | UTC+11:00 | Australian Eastern Daylight Time | Seasonal |
| ACST | UTC+09:30 | Australian Central Standard Time | Regional |
| ACDT | UTC+10:30 | Australian Central Daylight Time | Seasonal |
| AWST | UTC+08:00 | Australian Western Standard Time | No seasonal clock change |
| NZST | UTC+12:00 | New Zealand Standard Time | Seasonal pair with NZDT |
| NZDT | UTC+13:00 | New Zealand Daylight Time | Seasonal |
Abbreviations are labels, not safe conversion keys. Use a named regional identifier such as America/New_York or Asia/Kuala_Lumpur when a calculation must follow date-specific clock rules.
Why abbreviations are risky
Codes such as IST, CST and AST can refer to different offsets in different regions. Named IANA zones are safer for date-aware calculations.