Reading Outlook Calendar Work Hours

To the best of my knowledge, there are no Interfaces/properties exposed to retrieve the Outlook Calendar Work Hours (Start Time & End Time). However there is one easy way to retrieve Outlook Calendar Work Hours. We can read those values from registry. These values are stored under the following registry key:


You can easily find {version} in the key above from the Outlook Application instance in an Outlook Add In project, take first 4 characters of the version (e.g.: 15.0).

The two values under this key are:

  • CalDefStart for Start Time
  • CalDefEnd for End Time.

The data that these values store is minutes from mid-night. Read the value from the key, take date component of DateTime.Now and add the value (minutes) to find start/end time of the day based on those given in calendar settings.

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