The calendar selection allows the user to select the calendar and Day Length which times will be calculated based on.
This is a built in calendar and calculates times based on a continous calendar. All durations inside and outside business hours count and can only be used with "24 Hour Days" day length selection.
Default Business Hours or Custom Calendars
These calendars calculate times based on business calendar definitions that can be set by the JIRA admin from Time in Status settings. Only durations inside business hours count. Non-working days and holidays are excluded. Day length can be 24 Hour Days or Business Days.
Day length sets how long one day should be in the report output. This selection affects the output of report durations when View Format includes days.
24 Hour Days
1 day is 24 hours. Mostly used for continous reporting.
The length of 1 day is determined according to the Working Hours settings in calendar definition. Used when report contains more than 1 day durations and the report output is needed to show the business day count of durations.
Since this option affects only the duration calculations, Calendar selection is not visible for Count or Date report types.
Let's give an example to clarify the differences between calendars:
By default the business hours calendar is set to work from 09:00 - 17:00 and weekends are non-working days. If an issue was transitioned to "In Progress" on Friday at 16:00 and was transitioned to "Done" on Wednesday of next week at 16:00, different values will show for different calendar types and view formats. (See View Format section below about View Formats)
|Calendar Work Hours||Day Length||View Format = Hours||View Format = Days|
|7/24||24 Hour Days||120 hours||5 days||It is 120 hours or 5 days since nothing is excluded|
|24 Hour Days||24 hours||1 days||It is 24 business hours since only business hours are included and it is 1 day since 1 day is calculated as 24 hours|
|09:00-17:00||Business Days||24 hours||3 days||It is 24 business hours since only business hours are included and it is 3 days (3 business days) since 1 day is calculated as 8 hours|
24 Hour Days and Business Days reports produce the same output for durations shorter than one business day. For longer durations things change: For example a 4h duration is same for both report types but 25h for a 7/24 report is 1d1h for a 24 Hour Days report and 3d1h for a Business Days report. (presuming an 8 hr work day)