Time zone abbreviations can be confusing, partly because several different zones sometimes share the same three letters. Below is a reference for the most commonly used abbreviations.

North America

  • EST / EDT — Eastern Standard/Daylight Time, UTC-5 / UTC-4
  • CST / CDT — Central Standard/Daylight Time, UTC-6 / UTC-5
  • MST / MDT — Mountain Standard/Daylight Time, UTC-7 / UTC-6
  • PST / PDT — Pacific Standard/Daylight Time, UTC-8 / UTC-7
  • AKST / AKDT — Alaska Standard/Daylight Time, UTC-9 / UTC-8
  • HST — Hawaii Standard Time, UTC-10 (no DST)

Europe

  • GMT — Greenwich Mean Time, UTC+0
  • BST — British Summer Time, UTC+1
  • CET / CEST — Central European (Summer) Time, UTC+1 / UTC+2
  • EET / EEST — Eastern European (Summer) Time, UTC+2 / UTC+3
  • MSK — Moscow Standard Time, UTC+3 (no DST)

Asia & Middle East

  • IST — India Standard Time, UTC+5:30 (note: also used for Israel and Ireland Standard Time in other contexts, so context matters)
  • GST — Gulf Standard Time, UTC+4
  • CST — China Standard Time, UTC+8 (careful: shares an abbreviation with US Central Time)
  • JST — Japan Standard Time, UTC+9
  • KST — Korea Standard Time, UTC+9
  • SGT — Singapore Time, UTC+8

Oceania

  • AEST / AEDT — Australian Eastern Standard/Daylight Time, UTC+10 / UTC+11
  • ACST / ACDT — Australian Central Standard/Daylight Time, UTC+9:30 / UTC+10:30
  • AWST — Australian Western Standard Time, UTC+8 (no DST)
  • NZST / NZDT — New Zealand Standard/Daylight Time, UTC+12 / UTC+13

Why abbreviations can be ambiguous

Because there's no single global authority assigning time zone abbreviations, the same three letters sometimes refer to entirely different offsets depending on region — CST alone can mean US Central Standard Time, China Standard Time, or Cuba Standard Time. When precision matters, it's safer to reference a city name or the IANA time zone identifier (like America/New_York) rather than an abbreviation alone.