In this section, you can configure how the work (or, in other words, effort required to complete the task) is determined.
Tasks can be estimated either using Time Tracking or Story Points.
For both options you need to specify the default value, which will be used for tasks with no estimate defined.
For the Story Points option you also need to set the ratio, which will be used to convert Story Points into hours and back.
If you are working on a plan, where teams use both time tracking and story points, you can select both options. By default Time Tracking will be preferred. This means that Gantt chart will first be checking if an issue has an Original or Remaining Estimate defined. If it does, it will be used for calculating the task duration. If it doesn't, Gantt will check for the Story Points estimate and will try to use that. If none are available, the default defined for the time tracking option will be used.
If you adjust the task duration by changing the size of the task bar in the chart, Gantt chart will update the time tracking data even if the task estimate originally was in Story Points.
If you'd like to use story points instead, select the corresponding option ("Prefer Story Points over Time Tracking").
Please note, that the estimates define the amount of work - the exact duration of the task will depend on the amount of work and on the resource assigned to the task. Please check the Working with Resources section for more details.