How is the ahead/behind calculated for a sprint?

The ahead/behind indication is based on an estimate of how much available time is left in the sprint, compared to how much work remains to be done. The estimate of how much available time is left is calculated as follows:

1. If you specify the total available time for a team, all non-weekend workdays (so, Monday to Friday) are assumed to be workdays. The total available time is then distributed evenly across those workdays to obtain the available time per workday. The remaining available time is then calculated from the number of workdays left in the sprint, and the available time per workday.
2. If you specify the available time individually for each day, the remaining available time is calculated as the sum of the available time specified for each of the remaining days in the sprint.
3. For today, the current time of the day (in the local time zone of the team) is used to estimate how much of the available time is left today, assuming the work is done in normal office hours. So, in the morning, all of the available time of today is considered to be available; halfway during the workday, half of the time is considered to be available; and in the evening, none of the time today is considered to be available.