When I talk to colleagues I want to write "Let's meet 10am London / 11am Europe", but I want to use an abbreviation.

I used to write "10am GMT / 11am CET". But if it were daylight savings time this would be incorrect, and has tripped me up many times, like when I type into Google "10am GMT in CET".

This website claims that CET in common usage means either so that I am correct to use it:

Warning: Many sources define CET as a constant UTC+1. In common usage however, CET usually refers to the time observed in most of Europe, be it standard time or daylight saving time.

There was another question on here for US, that said PT is the correct term for the observed time in the Pacific time zone region, compared PST and PDT that depend on the time of year.

However, from http://mm.icann.org/pipermail/tz/2015-October/022798.html:

Generally speaking, CET = UTC+1, and CEST = UTC+2. Though in some contexts, CET may be used to identify the pair. It's slightly different than the US, as we have the generic term Pacific Time to cover both PST and PDT, but Europe doesn’t have such a generic term.

I am really surprised how difficult it is to find an acronym for the current observed time in a time zone region.

Also, if a time zone is the time in a region at a particular time of year, what is the official term for the geographic region that a time zone applies to?

There seems to be an official standard for an area Europe/Berlin, but what I am looking for is an acronym for a group of areas that respect the same time zone.

  • 1
    Very good question. I would like to specify our office hours in a contract and I'm struggling with the same thing (9 AM - 5 PM "CET or CEST - whatever applies at that particular day" is just not concise enough).
    – Heinzi
    Commented Sep 21, 2020 at 12:32
  • @Heinzi In our contracts, we say "[...] the hours of XX to XX Central European Time in winter, and Central European Summer Time in summer [...]"
    – Ama
    Commented Jul 15, 2021 at 9:19
  • Perhaps the first thing to point out is that the term "Daylight Saving" is never used in Britain and I doubt it is much understood in continental Europe. The US convention of inserting an S for standard, and D for "daylight" is an entirely new one on me, as I suspect it is in most of Europe. The UK is either on GMT (Greenwich Mean Time) or BST (British Summer Time). During WW2 Britain moved its clock ahead 2 hrs in summer (something to do with farming and harvesting) and it was known as "Double Summer Time" - though what the abbreviation was I'm not clear about.
    – WS2
    Commented Nov 9, 2021 at 23:47
  • 1
    GMT is the time used throughout the year (even when Britain is on BST) by the BBC World Service for its radio and TV broadcasts around the world. One is not much aware of the term UTC in Britain. We have abandoned feet and inches, pounds and ounces but never GMT. Greenwich is the centre of the world.
    – WS2
    Commented Nov 10, 2021 at 0:23
  • The problem with this question is that it assumes the same language is used in chronometry (the study of time when absolute precision and unambiguity is required) and when people are arranging meetings. If you want to arrange a meeting, you use terminology such as Paris Time or CET, or rely on your calendar software to sort it out; if you are developing GPS or ITS servers you explicitly reference UTC.
    – Stuart F
    Commented Nov 10, 2021 at 21:01

1 Answer 1


CEST or CEDT Central European Summer Time or Daylight Time respectively.

CET in the winter. (Central European Time).

These are from the linked source, timeandate.com

CET would be the general acronym similar to PT. But in the US people don't use PT. We'd say either Pacific (spelled out) or PST/PDT for the designation. (Note, in PST the S is for Standard, not Summer.)

So you could follow suit and say:

Central European or CET/CEST where appropriate.

Because the time only shifts twice a year, you just have to nail down your naming convention by time of year. Winter vs Summer.

  • I want a single acronym for both, like ET in the USA.
    – vaughan
    Commented Oct 21, 2019 at 18:22
  • @vaughan unfortunately I don't believe it exists. CST is already Central Standard Time. CET is the winter designation and CEST is the summer, though I'd likely use CEDT to avoid confusion with Central European Standard Time.
    – David M
    Commented Oct 21, 2019 at 18:26
  • Seems to be the standard adopted by the EU for naming
    – David M
    Commented Oct 21, 2019 at 18:28
  • The annoyance is that typing "10am AEST in CET" will use CET as Winter Time. I hope they just get rid of Summer Time in 2021 to clear this up.
    – vaughan
    Commented Oct 26, 2019 at 18:55
  • Easiest just to give one time, and to preface it with the most relevant location time.
    – user205876
    Commented Jul 12, 2021 at 23:14

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