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Adding a time zone to Outlook

Outlook for Windows has the ability to select the time zone for an appointment, but what if the zone you need isn’t on the drop down list?

Until Outlook 2007, Outlook only knew about one time zone and that’s the one currently set for Windows. All appointments are presumed to be in the current time zone (as defined by Windows).

Outlook 2007, at long last, added the ability to specify the time zone. Even better you can choose different time zones for the start and end of an appointment (for example a plane flight).

Let’s not dwell too much on how long it took Microsoft to add this obvious, if not essential, feature. It wasn’t a big task because the underlying database for Outlook has always been able to handle multiple time zones.

We’ll also pass over the astonishingly poor time zone display options in Outlook – effectively none except for a lame dual time zone scale that’s usually incomprehensible.

The list of time zones in Outlook 2007 is acquired from the Windows registry and is usually sufficient. The Microsoft time zone people do a good job of keeping that data current for time zones and daylight saving changes.

Interestingly, Windows Vista not only stores current time zone information but any variations in past years (ie when the DST arrangements have changed). This data could be very useful in fixing an ongoing problem with Outlook (especially if it works for future DST changes as well as past ones). We can only hope the Outlook development team starts making use of this data.

Despite those efforts there are some time zones not listed by Microsoft.

Some Office Watch readers in New Zealand have asked about Chatham Island (way off the east coast of New Zealand) which is +12:45 GMT. That’s 45 minutes earlier than New Zealand itself.

We’d be interested to hear about any other time zones missing from Windows, either time shifts like Chatham Island or the same base time but differing daylight savings rules. Let us know at

To add an appointment exactly in these time zones might require a little hack of Windows. This modest little hack of Windows is really only necessary if you regularly visit or are staying for some time in that time zone. For short stays or occasional use it’s probably not warranted and we have an alternative suggestion below.

Adding a time zone

The time zone data in the registry is complex (especially the TZI key) so it’s not a good idea to change the registry directly.

Microsoft did have a tool to edit the time zone part of the registry but it’s no longer available. You can try instead TZedit but we’ve not verified this tool, use at your own risk.

The best way is to find a closely matching time zone entry, preferably with the same daylight savings information and copy those details (for example with the Chatham Islands you would clone the New Zealand entry which shares the same daylight savings settings). TZedit doesn’t have a copy or clone command.

TZedit - main dialog.jpg image from Adding a time zone to Outlook at

1. Start TZedit

2. Find the source time zone, in this case New Zealand, click Edit and note down the details.

TZedit - New Zealand details.jpg image from Adding a time zone to Outlook at

3. Return to the main dialog and click New.

4. Enter the new details. The most important item is the Offset from GMT. DST details are copied from the New Zealand entry.
The labels and abbreviations are up to you. We’ve added the word ‘custom’ just to remind that this entry isn’t one maintained by Microsoft.

TZedit - Chatham Island details.jpg image from Adding a time zone to Outlook at

5. Close out of TZedit

Now start / restart Outlook to show the new details in the appointment list.

Outlook 2007 - custom time zone in action.jpg image from Adding a time zone to Outlook at

What’s displayed on another computer?

That’s all well and good for a single computer but what happens if the same appointment appears on another copy of Outlook which doesn’t have the custom time zone added?

That can happen if you’re working with Exchange Server or other central calendar resource.

The time offset is maintained when the appointment is displayed on the second computer. As usual, the appointment is displayed in the local time for that computer.

However, the custom time zone isn’t displayed in the time zone list – the local time zone on that computer is displayed instead.

You can edit the text fields of the appointment without touching the start and end details. However changing the date fields will reset the time zone setting and you’ll lose your custom time zone information.

For occasional use

Changing the Windows time zone data is probably not necessary for occasional use. If you’re just visiting the place for a short time, it’s a lot of trouble for a few appointments.

For occasional needs it might be sufficient to use a nearby time zone instead, entering the adjusted time in the Start and End fields (so the appointment shows up at the correct place in Outlook views and reminders trigger at the right time).

Note the correct local time in the subject or location fields like this:

Outlook 2007 - using in-built time zone for an unlisted TZ appointment .jpg image from Adding a time zone to Outlook at

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