EST, PST, IST and other time zone abbreviations
Learn when abbreviations mean a fixed offset, when they are ambiguous, and why city names prevent mistakes.
EST is not the same as Eastern Time all year
Eastern Standard Time (EST) is UTC−5. Eastern Daylight Time (EDT) is UTC−4. “Eastern Time” usually refers to a region that uses one or the other depending on the date.
The converter treats EST as the fixed UTC−5 offset. Choose New York when you mean local Eastern Time with date-based clock changes. The same distinction applies to PST and a city such as Los Angeles.
The ambiguity in CST and IST
CST can refer to US Central Standard Time, China Standard Time, or Cuba Standard Time. IST can refer to India Standard Time, Irish Standard Time, or Israel Standard Time. A short label without context is not a unique time zone.
Our reference choices explicitly label CST as US Central Standard Time, UTC−6, and IST as India Standard Time, UTC+5:30. For other meanings, select the city: Shanghai, Dublin, or Tel Aviv, for example.
A clear way to write a meeting time
Write the date, local time, city, and optionally the UTC offset: “15 September 2026, 9:00 am in New York (UTC−4).” This gives the reader enough context to understand the intended instant.
A shareable converter link or calendar event is even easier to use. It carries the exact instant and avoids relying on someone interpreting an abbreviation.
What an IANA time zone looks like
IANA identifiers such as Europe/Madrid and Asia/Kathmandu identify a set of local time rules. Their names often use a representative city, but can apply to many nearby places.
You can enter a full IANA identifier in our city search. Your browser must recognize the identifier for the calculation to work. Keep your browser and operating system current for recent changes.
Put it into practice.
Compare your cities, choose a date, and find a moment that works.
Open the time converter →Sources & further reading
Time zone rules and identifiers: IANA Time Zone Database. Time standards and clock terminology: NIST Time of Day FAQs. See how our converter calculates time for implementation details and limitations.