Working with custom fields

You can add additional input boxes to your Butler commands by using custom fields, which are available for Rules, Card Buttons, and Due Date commands. To work with custom fields, the board must be in a Trello Workspace with a paid subscription ( StandardPremium, or Enterprise). Trello users who previously enabled the Custom Fields Power-Up on a Trello board in a free Workspace will also have custom field options.

If you’re using Custom Fields with the “Add member to card” Butler action, this action currently doesn’t support fields that contain spaces (e.g. “Member name”).

Custom field variables

Note: Custom field variables are case-sensitive and need to be capitalized.

The value of a custom field can be obtained by using a variable in the form {{%Field Name}}


  • when custom field "Start Date" is set by anyone, post comment "The Start Date custom field was set to: {{%Start Date}}"

  • when a card is moved to list "Done" by anyone, add member @{{%Tester}} to the card, and post comment "@card Task with priority {{%Priority}} was completed and is ready for testing."

The value of a custom field that is used as a trigger can be referenced by using {customfieldvalue} .


when custom field "Priority" is set, for each card linked in the attachments, set custom field "Priority" to {customfieldvalue}

Custom field arithmetic

When setting the "Number" custom field, you can perform basic arithmetic operations such as addition, subtraction, multiplication, and division. You can also use numeric constants and parentheses to group arithmetic expressions.


when a card is moved to "This Week", set custom field "Total Points" to "{{%Design Points}} + {{%Dev Points}} + {{%QA Points}}"

Additional Help