Converters & time math
Timezone abbreviation lookup
What does EST, CEST, or AEST actually mean? Search the abbreviations you run into and get the real offset and region — with the ambiguous ones honestly flagged.
| Abbr | Name | Region | Offset |
|---|---|---|---|
| UTC | Coordinated Universal Time | Global | UTC+0 |
| GMT | Greenwich Mean Time | UK, West Africa | UTC+0 |
| WET | Western European Time | Portugal, Ireland | UTC+0 |
| BST | British Summer Time | UK (summer) | UTC+1 |
| CET | Central European Time | Continental Europe | UTC+1 |
| CEST | Central European Summer Time | Europe (summer) | UTC+2 |
| EET | Eastern European Time | Eastern Europe | UTC+2 |
| EEST | Eastern European Summer Time | Eastern Europe (summer) | UTC+3 |
| MSK | Moscow Standard Time | Russia (west) | UTC+3 |
| GST | Gulf Standard Time | UAE, Oman | UTC+4 |
| PKT | Pakistan Standard Time | Pakistan | UTC+5 |
| IST | India Standard Time | India, Sri Lanka | UTC+5:30 |
| IST | Irish Standard Time | Ireland (summer) | UTC+1 |
| BST | Bangladesh Standard Time | Bangladesh | UTC+6 |
| ICT | Indochina Time | Thailand, Vietnam | UTC+7 |
| CST | China Standard Time | China | UTC+8 |
| SGT | Singapore Time | Singapore | UTC+8 |
| HKT | Hong Kong Time | Hong Kong | UTC+8 |
| AWST | Australian Western Standard Time | Western Australia | UTC+8 |
| JST | Japan Standard Time | Japan | UTC+9 |
| KST | Korea Standard Time | South Korea | UTC+9 |
| ACST | Australian Central Standard Time | Central Australia | UTC+9:30 |
| AEST | Australian Eastern Standard Time | Eastern Australia | UTC+10 |
| AEDT | Australian Eastern Daylight Time | Eastern Australia (summer) | UTC+11 |
| NZST | New Zealand Standard Time | New Zealand | UTC+12 |
| HST | Hawaii Standard Time | Hawaii | UTC−10 |
| AKST | Alaska Standard Time | Alaska | UTC−9 |
| PST | Pacific Standard Time | US & Canada (west) | UTC−8 |
| PDT | Pacific Daylight Time | US & Canada (west, summer) | UTC−7 |
| MST | Mountain Standard Time | US & Canada (mountain) | UTC−7 |
| MDT | Mountain Daylight Time | US & Canada (mountain, summer) | UTC−6 |
| CST | Central Standard Time | US & Canada (central) | UTC−6 |
| CDT | Central Daylight Time | US & Canada (central, summer) | UTC−5 |
| EST | Eastern Standard Time | US & Canada (east) | UTC−5 |
| EDT | Eastern Daylight Time | US & Canada (east, summer) | UTC−4 |
| AST | Atlantic Standard Time | Caribbean, Canada (Atlantic) | UTC−4 |
| BRT | Brasília Time | Brazil (east) | UTC−3 |
Flagged abbreviations are ambiguous — IST, CST, and BST each mean different things in different regions. When in doubt, use the full IANA zone name.
How to use the timezone abbreviation lookup
Look up the abbreviation
Type the code you have found — EST, CET, AEST, IST — and see which zones and offsets it can refer to.
Check for collisions
Several abbreviations map to more than one real offset. If more than one result comes back, the abbreviation alone is not enough to interpret the timestamp.
Note standard versus daylight
Most regions have two codes: a standard one and a summer one. EST and EDT differ by an hour, and people write EST when they mean EDT constantly.
Translate to an IANA zone
Take the unambiguous zone identifier — America/New_York rather than EST — and use that anywhere the value gets stored or sent.
Why time zone abbreviations are unreliable
Abbreviations are not standardised and not unique. IST is India Standard Time (UTC+5:30), Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). CST covers North America's Central Standard Time (UTC−6), China Standard Time (UTC+8) and Cuba Standard Time (UTC−5). A timestamp labelled with either is genuinely ambiguous, and no amount of context always resolves it.
There is also the standard-versus-daylight mistake, which is close to universal. From March to November, the United States east coast is on EDT, not EST — yet almost everyone writes EST all year. Usually the reader guesses right; occasionally they do not, and a meeting is an hour off. "ET" is the honest way to write it when you mean "whatever the east coast is on".
This is exactly why the IANA time zone database uses geographic identifiers instead. America/New_York names a region with a history of rules, so it resolves correctly for any date, past or future, and cannot collide with a zone on another continent. Every serious date library and database speaks it.
The practical rule: read abbreviations, because people will keep sending them, but never write them into anything a machine will parse. In storage and in APIs, use UTC instants or IANA zone identifiers, and keep the abbreviation for the human-facing label at the very end.
When you'd reach for it
Decoding an email
Work out which offset a colleague meant when they wrote a bare abbreviation.
Reading a schedule
Interpret a conference or broadcast time listed with a code you do not recognise.
Migrating stored data
Map legacy abbreviation columns onto proper IANA identifiers.
Reviewing a bug report
Establish what a timestamp in an issue actually referred to.
Writing documentation
Choose an unambiguous way to express times for an international readership.
Checking a contract
Confirm the offset a legally significant deadline was expressed in.
Questions & answers
- Why is one abbreviation listed twice?
- Some abbreviations are genuinely ambiguous. IST means both India Standard Time (+5:30) and Irish Standard Time (+1); CST covers US Central (−6) and China Standard (+8). Both meanings are listed and flagged.
- Are standard and daylight abbreviations different?
- Yes. Many zones switch abbreviation in summer — EST becomes EDT, CET becomes CEST, PST becomes PDT — each with a different offset. Both are included.
- Should I use abbreviations in code or invites?
- Prefer full IANA names like America/New_York. Abbreviations are convenient for reading but ambiguous, so they're risky for scheduling and software.