Time Zone Abbreviation Lookup

Time Zone Abbreviations Explained

Type an abbreviation such as PST, CET, or IST into the search box and the tool returns its full name, UTC offset, and the regions that use it. You can also search by zone name or by country, so “Japan” finds JST just as quickly as the abbreviation itself. The database covers roughly 40 of the abbreviations you will actually meet in emails, meeting invites, flight itineraries, and server logs.

Standard vs. Daylight Abbreviations

North American zones come in pairs: the “S” form is standard (winter) time and the “D” form is daylight (summer) time, one hour ahead. So EST is UTC−5 but EDT is UTC−4; PST is UTC−8 but PDT is UTC−7. A very common mistake is writing “EST” in July, when New York is actually on EDT — if someone sends you a summer meeting time “in EST,” they almost always mean current Eastern Time, not literal UTC−5. European zones use a different pattern: CET (UTC+1) becomes CEST (UTC+2) in summer, and the UK swaps GMT for BST, British Summer Time.

The Ambiguity Problem

Abbreviations are not globally unique, which is why professionals prefer UTC offsets or IANA names like America/Chicago. Famous collisions include:

• CST — Central Standard Time (UTC−6) in North America, but also China Standard Time (UTC+8) and Cuba Standard Time (UTC−5).
• IST — India Standard Time (UTC+5:30), Irish Standard Time (UTC+1), and Israel Standard Time (UTC+2).
• BST — British Summer Time (UTC+1) but also Bangladesh Standard Time (UTC+6).
• AST — Atlantic Standard Time (UTC−4) and Arabia Standard Time (UTC+3).

When an abbreviation is ambiguous, context decides: a Shanghai supplier writing “CST” means UTC+8, while a Chicago colleague means UTC−6 (or UTC−5 in summer). The lookup lists each meaning separately with its regions so you can pick the right one.

GMT vs. UTC

GMT (Greenwich Mean Time) and UTC (Coordinated Universal Time) share the same offset of zero and are interchangeable for everyday scheduling. Technically, GMT is a time zone historically based on the sun's position over the Greenwich meridian, while UTC is the modern atomic-clock standard that the world's timekeeping is actually defined against. Aviation and the military call it Zulu time (Z).

Not Every Zone Is a Whole Hour

Several zones sit at half- or quarter-hour offsets: India (IST, UTC+5:30), Newfoundland (NST, UTC−3:30), and Nepal (NPT, UTC+5:45). If a conversion ever comes out 30 or 45 minutes “wrong,” one of these zones is usually involved.