Understanding and using Time Zone Support for iOS, iCal, and MobileMe Calendar

  • Last Modified: July 06, 2011
  • Article: HT4504
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The Calendar app on iOS devices, iCal on Mac OS X, and the Calendar at me.com offer a feature called Time Zone Support. This article explains what Time Zone Support does, when it's appropriate to use, and when it's not necessary.

Products Affected

iPhone, iCal, MobileMe, iPad, MobileMe Calendar

What is Time Zone Support?

Time Zone Support allows you to create events and view calendars in time zones other than your computer's or device's default time zone, while still retaining the ability to use your default time zone. Basically it allows you to set time zones "on the fly" for each event in your calendar. In some clients, such as iCal, it allows you to toggle the time zones of your entire calendar. For example, if you are in the Pacific time zone (Pacific time), but you wish to create or view events for the eastern time zone (ET), Time Zone Support allows you to do so.

If Time Zone Support is on, your calendar will not update if you move between time zones. For example, if you have a meeting at 10 a.m. Pacific time in California, and you fly to New York, that meeting will still show up at 10 a.m. on your iOS calendar.

If Time Zone Support is off, your calendar moves as you move, that is, the time zone settings update as you change time zones. For example, if you have that same meeting at 10 a.m. Pacific time in California and fly to New York, your calendar items will be shown in local (eastern) time. So your meeting at 10 a.m. Pacific time will show up at 1 p.m. ET. If you expected to call in to such a meeting, 1 p.m. eastern time would be the correct time to do so. If you had time zone support on, you could end up calling in at 7 a.m., which would be a bit early.

Where is Time Zone Support on by default?

Time Zone Support is on by default in your iOS Calendar app.

Time Zone Support is off by default in iCal in Mac OS X and MobileMe Calendar.

Should I use Time Zone Support?

If you frequently travel and need to view and schedule events in other time zones, you may wish to use Time Zone Support while on the go. However, even for travelers, unless you wish to create and view events in multiple time zones at the same time, the introduction of Location Services has made Time Zone Support less necessary than it used to be. Location Services can automatically update the clock settings on your Mac, iPhone, iPad, or iPod touch when your physical time zone changes (if for example, you fly from New York to San Francisco). Location Services updates your calendars so they can be viewed and edited in your current time zone.

To avoid any confusion caused by Time Zone Support and Location Services:

  • Unless you plan on actively creating events in multiple time zones (for example, if you are in San Francisco, but want to create or view events in New York time), you will probably want to turn Time Zone Support off for your computer and iOS Devices (iPhone, iPad, or iPod touch). That way, as long as the proper time zone is set on your iOS device, the Date and Time system preferences on your Mac, and on your MobileMe account, your calendars and their events should be unified and consistent across all applications and services without much effort.

    Disabling Time Zone Support and using Location Services is the best option for most users as well as travelers who want consistency in their calendars and do not wish to create or view events in time zones other than the one they are in.

  • If you wish to use Time Zone Support to create and view events in multiple time zones simultaneously, make sure you know in which time zone you are creating events and in which time zone you are viewing all your calendars.

    Keep in mind that you can easily view events in one time zone and create them in another with Time Zone Support. For example, you could view your calendar in Pacific time and create new events in eastern time. It is especially important to be aware of these settings if you are changing time zones, because your last active setting is usually what future events are based upon and not necessarily the time zone you are in (unlike the default behavior in Location Services).

    For iOS devices, if you want to create or edit events for a different time zone, change the time zone in the Time Zone Support settings, then open the Calendar application to create or edit your events for that time zone. Once finished, you may change your Time Zone Support settings back to the time zone of your current location.

Additional Information

Please see the following articles for more information about configuring your system-wide Time Zone settings as well as calendar-specific Time Zone Support:

Date and Time Defaults

Location Services

Time Zone Support

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