Time zone abbreviations
What do EST, PST, CET, GMT and IST actually mean? This glossary lists the common time zone abbreviations with their full names, UTC offsets and the regions that use them — including the ones that are shared by more than one zone. 34 codes, west to east.
Abbreviations A–Z by offset
| Code | Name | UTC offset | Used in |
|---|---|---|---|
| HST | Hawaii Standard Time | UTC-10 | Hawaii |
| AKST | Alaska Standard Time | UTC-9 | Alaska (winter) |
| PST | Pacific Standard Time | UTC-8 | US & Canada West Coast (winter) |
| MST | Mountain Standard Time | UTC-7 | US Mountain West (winter) |
| PDT | Pacific Daylight Time | UTC-7 | US & Canada West Coast (summer) |
| CST | Central Standard Time | UTC-6 | US & Canada central (winter) |
| MDT | Mountain Daylight Time | UTC-6 | US Mountain West (summer) |
| EST | Eastern Standard Time | UTC-5 | US & Canada East Coast (winter) |
| CDT | Central Daylight Time | UTC-5 | US & Canada central (summer) |
| EDT | Eastern Daylight Time | UTC-4 | US & Canada East Coast (summer) |
| AST | Atlantic Standard Time | UTC-4 | Atlantic Canada, Caribbean |
| UTC | Coordinated Universal Time | UTC | Global reference |
| GMT | Greenwich Mean Time | UTC | UK (winter), West Africa |
| WET | Western European Time | UTC | Portugal, western Europe (winter) |
| BST | British Summer Time | UTC+1 | United Kingdom (summer) |
| WEST | Western European Summer Time | UTC+1 | Portugal, western Europe (summer) |
| CET | Central European Time | UTC+1 | Much of Europe (winter) |
| CEST | Central European Summer Time | UTC+2 | Much of Europe (summer) |
| EET | Eastern European Time | UTC+2 | Eastern Europe, Greece, Egypt (winter) |
| EEST | Eastern European Summer Time | UTC+3 | Eastern Europe, Greece (summer) |
| MSK | Moscow Standard Time | UTC+3 | Western Russia |
| GST | Gulf Standard Time | UTC+4 | UAE, Oman |
| PKT | Pakistan Standard Time | UTC+5 | Pakistan |
| IST | India Standard Time | UTC+5:30 | India, Sri Lanka |
| HKT | Hong Kong Time | UTC+8 | Hong Kong |
| SGT | Singapore Time | UTC+8 | Singapore |
| AWST | Australian Western Standard Time | UTC+8 | Western Australia |
| JST | Japan Standard Time | UTC+9 | Japan |
| KST | Korea Standard Time | UTC+9 | South Korea |
| ACST | Australian Central Standard Time | UTC+9:30 | Central Australia (winter) |
| AEST | Australian Eastern Standard Time | UTC+10 | Eastern Australia (winter) |
| AEDT | Australian Eastern Daylight Time | UTC+11 | Eastern Australia (summer) |
| NZST | New Zealand Standard Time | UTC+12 | New Zealand (winter) |
| NZDT | New Zealand Daylight Time | UTC+13 | New Zealand (summer) |
How to read time zone abbreviations
A time zone abbreviation is a short label for an offset from Coordinated Universal Time (UTC). Many regions use two through the year: a standard-time code in winter and a daylight-saving code in summer that runs one hour ahead. So the US East Coast is EST (UTC-5) in winter and EDT (UTC-4) in summer; central Europe is CET then CEST.
The catch is that abbreviations are neither official nor unique. "CST" means three different things depending on whether you are in Chicago, Shanghai or Havana. When a time really matters — booking a call or a flight — quote the UTC offset or the IANA zone name (like America/New_York) instead of the abbreviation.
Frequently asked questions
- Are time zone abbreviations official?
- No. Abbreviations like EST, CET or IST are common shorthand but are not standardised or guaranteed unique — several are shared by more than one zone. For unambiguous scheduling, use the IANA zone name or the UTC offset.
- Why does the same abbreviation mean different times?
- Because they grew up independently around the world. "CST" is US Central Standard Time (UTC-6) but also China Standard Time (UTC+8) and Cuba Standard Time. "IST" covers India, Ireland and Israel — three different offsets. The context usually makes clear which is meant.
- What is the difference between a standard and a daylight abbreviation?
- Many regions use two abbreviations a year: a standard-time one in winter (EST, PST, CET) and a daylight-saving one in summer that is one hour ahead (EDT, PDT, CEST). This glossary links each pair together.