EST, EDT or ET? Standard time versus local time
By the Time Aligner project · Content revision:
Use a city or ET when you mean the clock time in a place on a particular date. Use EST only when you mean the fixed offset UTC−05:00. In summer, New York observes EDT (UTC−04:00), so treating a New York appointment as EST moves it by an hour.
The abbreviations describe different things
| Choice | Offset | Use it for |
|---|---|---|
| EST | UTC−05:00, fixed | A time explicitly given in standard time |
| EDT | UTC−04:00, fixed | A time explicitly given in daylight time |
| ET / New York | UTC−05:00 or UTC−04:00 | An appointment on the local calendar |
The same distinction applies to PST/PDT/PT and CST/CDT/CT. Abbreviations can also be ambiguous internationally: CST may refer to Central Standard Time or China Standard Time. Choosing a city removes that naming ambiguity. This tool’s IST means India Standard Time, UTC+05:30; use a city for Ireland or Israel.
Example: noon in New York to India
12:00 EST is 22:30 India Standard Time on every date: India is 10 hours 30 minutes ahead of that fixed offset. On 15 July 2026, however, noon in New York is 21:30 in Kolkata because New York is on EDT. On 15 January 2026, noon in New York is 22:30 in Kolkata.
Convert 12pm EST to IST for the fixed example, or convert New York to Kolkata and select the appointment date. For the reverse direction, IST to EST subtracts 10 hours 30 minutes and may land on the previous date.
Why New York and London are sometimes only four hours apart
The US changes clocks on the second Sunday in March and the first Sunday in November. The UK changes on the last Sundays in March and October. In 2026 the dates are 8 March and 1 November in New York, and 29 March and 25 October in London.
For weekdays from 9–27 March 2026 and 26–30 October 2026, London is four hours ahead of New York. For most other weekdays it is five hours ahead. At 09:00 in New York on 16 March, London is at 13:00; on 15 April, it is at 14:00. The Sundays containing the changes have transitions during the day, so always convert a specific time.
New York to London shows the selected date’s offsets and the overlap between 09:00–17:00 weekdays. Check both sides of a clock-change week before booking a recurring meeting; a one-off calendar export does not establish a recurrence rule.
Handle a missing or repeated hour
In New York on 8 March 2026, 02:30 does not exist: the clock jumps from 01:59 to 03:00. On 1 November, 01:30 occurs twice. Choose the first or second occurrence before exporting; the UTC instant distinguishes them. Do not resolve a missing time by silently assuming a different hour.
A reliable scheduling workflow
- Select two cities and the meeting date.
- Check the result date as well as the time, especially across midnight.
- For a repeated hour, select the intended occurrence.
- Select a valid start/end range, then export the calendar file and verify the imported appointment.
- For a recurring series, check the next clock-change dates in both places and use the calendar application’s recurrence controls.
Sources and scope
Rules: NIST daylight saving time, UK clock-change dates, and the IANA time zone database. These examples describe New York, London and Kolkata, not every region in the US, Europe or Asia. See calculation assumptions for runtime data limits.