Microsoft Office Outlook uses the country/region settings for your computer to determine how the times appear.

For example, in Calendar in the month view, if you are using the default settings for the United States, Outlook displays a 12-hour clock. After 12:59 P.M., the time is displayed as 1 P.M. Other countries/regions use a 24-hour clock.

You can change how the clock appears in your display. However, changing this display is an option provided by the operating system, not Outlook.

Change the time settings in Windows

Based on the operating system that you are using, do one of the following:

• Windows Vista  
  1. In Windows, click the Start button.
  2. Click Control Panel, click Clock, Language, and Region.

      Note   If you are using Control Panel in Classic View, double-click Regional and Language Options, and then skip to step 3.

  3. Click Regional and Lanugage Options.
  4. Click Customize this format.
  5. On the Time tab, do one of the following:
     • Change Time format to HH:mm:ss for a 24-hour clock.
     • Change Time format to hh:mm:ss tt for a 12-hour clock.
• Microsoft Windows Server 2003  
  1. In Control Panel, double-click Regional Options.
  2. In Regional Options, click Customize.
  3. Click the Time tab.
  4. Do one of the following:
     • Change Time format to HH:mm:ss for a 24-hour clock.
     • Change Time format to hh:mm:ss tt for a 12-hour clock.
• Microsoft Windows XP  
  1. In Control Panel, click Date, Time, Language, and Regional Options.

      Note   If you are using Control Panel in Classic View, double-click Regional and Language Options, and then skip to step 3.

  2. Click Regional and Language Options.
  3. Click Customize.
  4. Click the Time tab.
  5. Do one of the following:
     • Change Time format to HH:mm:ss for a 24-hour clock.
     • Change Time format to hh:mm:ss tt for a 12-hour clock.