Well, I’m back from vacation and thanks to this morning’s time change (at least in the US), very glad to be back into Eastern Standard Time! Warning: Timezone misunderstandings are a huge pet peeve of mine. Ask my friends. 🙂
This is the easy part of the year — the half of the year where no matter how little someone understands timezones, they can blithely state that the meeting is at “2pm EST” or that they work “8-5 EST” and actually be right! During Daylight Saving Time (essentially, April -> October in the US), lots of people I interact with still refer to Eastern Standard Time, totally oblivious to the fact that they are referencing a different timezone than they’re currently in.
So, here’s the short version — a pocket guide, if you will:
- Greenwich Mean Time (GMT/UTC) is a fixed timezone. It never changes.
- Eastern Standard Time (EST) is also a fixed timezone. It is (always) GMT-5:00.
- Eastern Daylight Time (EDT) is also a fixed timezone. It is (always) GMT-4:00.
In (most of) the US, we simply jump back and forth an hour twice each year — we switch into a different timezone. EST is always 5 hours behind GMT. EDT is always 4 hours behind GMT.
And here’s the important thing: If you say the meeting is at 2pm EST… during July…. in Charlotte, NC… do you mean that we should show up at 3pm EDT? Should I just assume you don’t understand timezones when I put the meeting into my Outlook calendar with a 2pm EDT start time? Computers understand timezones, of course!
See these links for additional information:
(this post dedicated to Michael, Scott and Jodi – who get to listen to me rant on this topic at least twice each year). 🙂
Updated Jan 17, 2005 – I’ve written a utility that’ll tell you how your machine’s timezone settings are configured. This won’t tell you which timezone you’re in (that’d be a neat trick!), but it’ll tell you which timezone your machine is currently configured for plus all the DST stuff. Get it here.