When is 1st of February 00:00 (EST) in GMT time in the UK? What time and date will be in the UK?

Is it on 2nd of February or 1st of February at 05:00am?

closed as off-topic by Giorgio, Tor-Einar Jarnbjo, Ali Awan, user67108, Henning Makholm Jan 31 '18 at 12:33

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    I'm voting to close this question as off-topic because it's not related to travel. – Giorgio Jan 30 '18 at 19:00
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    There is no 24:00 in a 24h clock. – Tor-Einar Jarnbjo Jan 30 '18 at 19:02
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    @Giorgio While there is no explicit tie to travel, there is tremendous cross-cultural confusion when it comes to marking the beginning and end of the day, or when a.m. and p.m. properly begin and end. I know it's something I always feel I need to triple-check, especially when crossing the date line, so I think the question should stand. – choster Jan 30 '18 at 19:13
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    @phoog Yes, we should tell them that what they are saying does not make sense or is ambiguous and ask for clarification. Instead of being a deliberate use of a quirk from a technical standard, saying 24:00 could just as well be an unintentional mistake from someone used to the 12-hour clock and hours going from 1 to 12, who assumes that 24:00 is the hour before 1:00, just as 12:00 a.m. is the hour before 1:00 a.m. – Tor-Einar Jarnbjo Jan 30 '18 at 23:23
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    @dda It's actually fairly common in Japan, where I've seen it for instance used in opening hours of hotel onsens etc. (And apparently also for [anime.stackexchange.com/a/4020](TV show timings). This is not really due to people being not used to the 24-hour system, which is used in Japan (together with the 12-hours system). – drat Jan 31 '18 at 8:34

ISO 8601 uses 24:00 specifically for midnight at the end of a day, and 00:00 for midnight at the start of a day. Thus, a flight that departs at 24:00 on Thursday, 1 February, U.S. Eastern Time is equivalent to one departing at 00:00 on Friday, 2 February, U.S. Eastern Time. Greenwich Mean Time would be 05:00 on Friday, 2 February.

U.S. Daylight Saving Time and British Summer Time begin and end on different dates, however, so check the offset if you are traveling during around the transitions.

In practice, I think carriers try to avoid the ambiguity and the customer service problems it will produce by scheduling a few minutes before or after, especially in the U.S. where the 12-hour clock is still predominant, even in travel settings.

For a magisterial treatment on the ambiguity see Why is 11 am + 1 hour == 12:00 pm? at English Language Learners.

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    Greenwich Mean Time and Eastern Standard Time are 5 hours apart throughout the year. A flight departing at midnight in July departs at midnight Eastern Daylight Time, which is four hours earlier than GMT, but five hours earlier than British Summer Time. – phoog Jan 30 '18 at 20:25

EST is UTC-5, and 24:00 is usually a fairly uncommon but technically standard (ISO 8601) way of saying 00:00 the following day, so I would interpret this at 0500 February 2. However, it would be safest to check.

Note that once daylight savings time is in effect, some misuse EST when the region will really be on EDT (UTC-4), but this doesn't begin until March. Of course, once the UK goes on British Summer Time (BST) then they'll be UTC+1 as well.

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    ISO 8601 doesn't count as a standard? – phoog Jan 30 '18 at 20:18
  • @phoog I stand corrected then. – Jim MacKenzie Jan 31 '18 at 14:26

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