Number of open subtasks

Use case

Count the number of subtasks, which are open (in status category To Do or In Progress).

Create a new Calculated Number Field (by JWT) custom field and name it properly.

Providing a description will help you to identify what the custom field does but this step is optional

Add the following expression:

Math expression for Calculated Number field:

count(filterByPredicate(subtasks(), ^%{00144} = "To Do" OR ^%{00144} = "In Progress"))

%{00144} is the field code for Status Category
The ^ is used for referencing the field values of the issue list l - in this case, subtasks(). Without, the field codes would refer to the current issue.
[Schema for function filterByPredicate(issue list l, boolean expression predicate)]

To achieve this, the following functions are used:

Once configured and added to an issue screen, the result will look like this:

If you still have questions, feel free to refer to our support team.