Gantt Suite for Jira v 4.0.x: Task duration calculation explained

Task duration is calculated using worktime only. Non-working time is excluded.

Non-working time is:

  1. days marked as non-working

  2. hours marked as non-working

Consider the following tasks:

The dates, March 14th and March 15th present a weekend, so they are displayed in grey color when chart scale is set to Day.
Working hours are 9:00 am till 5:00 pm (8hrs).

All of the above tasks have the same duration that equals one day (8hrs), and here is why:

The task “PROJ-7: a” has 4hrs on March13th and 4hrs on March16th.

The task “PROJ-6: b“ starts at 9:00 am and ends at 5:00 pm, March 13th. All the hours are working hours, so all of them are included into task duration. Resulting in 8hrs..

The task “PROJ-5:c“ starts at 12:00 am and ends at 5:00 pm, March 13th. Time from 12:00 am till 9:00 am is ignored as non-working, thus only the time frame 9:00 am-5:00 pm is taken into account, resulting in 8hrs.

To conclude, longer task displayed on a chart doesn’t always mean longer task duration.

How exactly task work and task duration are calculated?

Task work

By default, task work and task duration are equal. Set task duration to distribute total task work per days, on Edit dialog.

For instance, task work is 1 day but you plan to work on the task for 2h per day. In such case, you’ll edit the task duration by inserting “4d” into Duration field:

With other words, you are spreading the 1 day of work on the task per 4 days which results in 2 hours of work per day.

Task duration

Duration becomes work logged + remaining, where remaining is taken from the Jira issue. Each time you log work, Jira asks for remaining time. Task having remaining time 0m is treated as completed.

If task has no work logged, and no Remaining Estimate is specified, then task duration becomes one day, by default. Blank field for task duration, on Edit Task dialog, means that task duration and task work are equal.


If a task has work logged, the duration can’t be set less than the amount of logged work.