Time Zone Abbreviations Directory (EST, PST, CST, CET, GMT)
A comprehensive reference table of commonly used global time zone abbreviations, their official full names, UTC offsets, and representative geographic regions. All abbreviations are anchored to Coordinated Universal Time (UTC). Note that seasonal transitions change many acronyms (e.g. EST shifts to EDT, and GMT shifts to BST)โlearn more in our Daylight Saving Time (DST) Guide, or browse cities in the Time Zones Directory.
Alphabetical Time Zone Abbreviations Table
Commonly Confused Time Zone Acronyms & Disambiguation
Because time zone abbreviations are not universally unique standard identifiers, several three-letter acronyms are shared by multiple regions on opposite sides of the planet. Schedulers must exercise caution when using the following abbreviations:
- CST: Can designate Central Standard Time in North America (UTC-6:00), China Standard Time in East Asia (UTC+8:00), or Cuba Standard Time (UTC-5:00)โrepresenting a massive 14-hour difference between Chicago and Beijing.
- BST: Can refer to British Summer Time in the United Kingdom (UTC+1:00) or Bangladesh Standard Time in South Asia (UTC+6:00)โa 5-hour difference.
- IST: Can represent India Standard Time (UTC+5:30), Israel Standard Time (UTC+2:00), or Irish Standard Time (UTC+1:00).
- AST: Can refer to Atlantic Standard Time in the Americas (UTC-4:00) or Arabia Standard Time in the Middle East (UTC+3:00)โa 7-hour discrepancy.
Best Practice: When coordinating cross-border meetings, always pair the acronym with its numerical UTC offset (e.g., CST (UTC-6)) or generate an automatic local-time invite using our Shareable Event Link Tool.
Convert Any Time Zone
Use our interactive converter to calculate time across any of these abbreviations instantly, or view them side-by-side on our live world clock.
Frequently Asked Questions
Essential answers on global time zone acronyms, duplicate abbreviations, and disambiguation.
What is a time zone abbreviation?
A time zone abbreviation is a short alphabetic code (typically 3 to 5 letters, such as EST, PST, CET, or JST) used to represent a specific civil time zone and its associated offset.
What do EST and EDT mean?
EST stands for Eastern Standard Time (UTC-5:00), observed in eastern North America during winter. EDT stands for Eastern Daylight Time (UTC-4:00), observed when clocks advance one hour during spring and summer.
What do PST and PDT mean?
PST stands for Pacific Standard Time (UTC-8:00), observed on the West Coast of North America during winter. PDT stands for Pacific Daylight Time (UTC-7:00), observed during summer daylight saving months.
What is the difference between GMT and UTC?
UTC is the global reference standard maintained by atomic clocks, whereas GMT is a traditional civil time zone. As abbreviations, UTC is used in technical and aviation specifications, while GMT is commonly referenced in European and African civil schedules.
Why can the same time-zone abbreviation mean different things?
Time zone acronyms are not universally standardized. For example, CST can mean Central Standard Time in North America (UTC-6:00), China Standard Time in Asia (UTC+8:00), or Cuba Standard Time (UTC-5:00).
Should I use a city or a time-zone abbreviation when converting time?
Using a city name is significantly more reliable than an abbreviation because city identifiers automatically resolve ambiguous acronyms and account for local daylight saving schedules.
What is the difference between standard time and daylight time?
Standard time is a region baseline civil time (e.g., EST or PST). Daylight time is the temporary one-hour advance applied during summer months to prolong evening daylight (e.g., EDT or PDT).