Daylight Saving Time Explained

March 6, 2013

Many–if not most–regions of the world use daylight saving time (summer time) for about half a year. For example, Eastern Standard Time (EST), which is Greenwich Mean Time (GMT) minus 5 hours (GMT-5:00), becomes Eastern Daylight Time (EDT), which is GMT minus 4 hours (GMT-4:00); and the time in Western Europe (e.g., Zurich) goes from GMT+1:00 to GMT+2:00.

When creating a Doodle poll, the poll creator can set a time zone so that the times she chooses for the poll options are with respect to that time zone. However, Doodle seems to only offer time zones for winter time. For example, “(GMT-5:00) EST” is available, but “(GMT-4:00) EDT” seems not to be; “(GMT+1:00) Zurich” is available, but “(GMT+2:00) Zurich” seems not to be. Furthermore, a poll’s options might feature both dates that lie in winter time and dates that lie in summer time.

So what are poll creators and poll participants supposed to do? First and foremost, don’t worry! Simply choose the “normal” time zone for your region without concern for the current time or the dates & times of the respective poll. For example, a user in New York always chooses “(GMT-5:00) EST” while a user in Zurich always chooses “(GMT+1:00) Zurich”. Behind the curtain, Doodle (or rather the Java platform that Doodle is based on) does its summer-time magic if need be.

Here’s an example: http://doodle.com/ehbn7guem4tq4m4f. A company with an office in New York and an office in Zurich wants all employees to be on a conference call. An employee from the New York office sets a Doodle poll up, always suggesting 9 to 11 AM.

Example poll set to New York time

Most of the year, the time difference between New York and Zurich is 6 hours (GMT-5 -> GMT+1 or GMT-4 -> GMT+2), so 9 to 11 AM typically becomes 3 to 5 PM. However, daylight saving time begins one week earlier in New York and ends one week later, so for two weeks per year, the time difference is only 5 hours (GMT-4 -> GMT+1) and 9 to 10 AM becomes 2 to 4 PM during those two weeks (cf. March 11 and 13 as well as October 28 and 30).

Example poll set to Zurich time

None of the users has to worry about that, either, as Doodle takes care of any and all necessary conversions. And everybody is on the same call at the right time!

3 Responses to “Daylight Saving Time Explained”

  1. Rosie Says:

    I’m glad to know that the scripts are working properly in the background.

    Since the only time-zone you ever use is the “normal” one for whatever region, have you considered using PT for Pacific Time rather than PST for Pacific Standard Time? Since you give the location in parentheses, people would know which PT this would stand for in the event there were other PT time zones also.

    Having said that, please know that I think the Doodle time-zone feature is really great! (…whereas, I avoid using time-zone in Google calendars like the plague because it has caused some problems when relying on it.)

  2. Brian Says:

    I agree that you should list it as PT vs PST, it’s confusing when trying to make sure I’m on the right time zone. If someone in MDT gives options for a call, and I have my time zone set as “CST”, then without reading this blog post, I assume that means Central Standard Time and I need to know CDT, so I’m wondering if they put the times in under the correct time zone. Some states don’t change at all, so I could see instances where you’d want to know both time zones. How does this work for people in Arizona?

    This is a GREAT tool for saving time and reducing confusion when scheduling with a large number of people…so long as it’s not confusing itself.

  3. Mark Says:

    It gets really confusing when the time zone changes name. I was recently enrolled in a webinar from the UK and all of the sudden the time zone changed from GMT to BST.

    I had no idea what was going on and what time i had to attend the webinar. Thank God for the various time zone converting websites around the web.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 13,164 other followers