Americas Time Zone Abbreviations
EST — Eastern Standard Time, UTC-5. Used by New York, Miami, Toronto in winter. EDT — Eastern Daylight Time, UTC-4. Same region in summer. CST — Central Standard Time, UTC-6. Chicago, Dallas, Houston in winter. PST — Pacific Standard Time, UTC-8. Los Angeles, Seattle, Vancouver in winter. PDT — Pacific Daylight Time, UTC-7. Same region in summer. MST — Mountain Standard Time, UTC-7. Denver, Phoenix (year-round for Arizona). BRT — Brasilia Time, UTC-3. Used in Brazil year-round.
Europe & Africa Time Zone Abbreviations
GMT — Greenwich Mean Time, UTC+0. Used in the UK in winter, Ireland, Iceland, Portugal, West Africa. BST — British Summer Time, UTC+1. UK in summer. CET — Central European Time, UTC+1. France, Germany, Italy, Spain, Poland in winter. CEST — Central European Summer Time, UTC+2. Same countries in summer. EET — Eastern European Time, UTC+2. Finland, Greece, Romania in winter.
Asia & Pacific Time Zone Abbreviations
IST — India Standard Time, UTC+5:30. Entire India, year-round. GST — Gulf Standard Time, UTC+4. UAE, Oman. PKT — Pakistan Standard Time, UTC+5. SGT — Singapore Time, UTC+8. Singapore, Malaysia. HKT — Hong Kong Time, UTC+8. CST — China Standard Time, UTC+8 (same abbreviation as US Central, be careful!). JST — Japan Standard Time, UTC+9. AEST — Australian Eastern Standard Time, UTC+10. Sydney in winter. AEDT — Australian Eastern Daylight Time, UTC+11. Sydney in summer.
Why Abbreviations Can Be Ambiguous
CST is used for both US Central Standard Time (UTC-6) AND China Standard Time (UTC+8) — a 14-hour difference! IST is used for India Standard Time (UTC+5:30), Ireland Standard Time (UTC+1), and Israel Standard Time (UTC+2). Always confirm the UTC offset alongside the abbreviation, especially in international contexts.