Using Formulas to Calculate Field Values
Amazing Fields lets you calculate field values automatically using formulas, similar to how you'd use Excel or Google Sheets. This article explains how to set up formulas, reference other fields (including fields from other cards), and handle common edge cases.
Use this article if you want to automatically compute values like totals, profit margins, durations, or conditional outputs based on data already on your Trello cards.
See Formulas in Action: Create a board from the Field Formula Template. Then open Amazing Fields settings to explore working examples.
Setting up a formula
Formulas can be applied to Text, Number, and Checkbox field types.
Formulas are a supporter-only feature. The user configuring the formula must be a supporter, but once set up, the formula works for all users and boards without restriction. See [link support article] for more.
To set up a formula:
- Open Amazing Fields Settings by clicking the Amazing Fields icon in the top-right corner of the board.
- Select the field you want to calculate automatically.
- Enable "Calculate field value using formula."
- Start typing in the formula you would like.
- Use "+ Field" to insert references to other fields.
Once enabled, the field becomes read-only. Amazing Fields updates it automatically whenever any other field on the card changes, including changes made by linked custom fields.
Note that formulas are not evaluated in real time while you're editing. To test a new formula, save it and then make a change to any field on the card to trigger a recalculation.
If a formula fails to evaluate, Amazing Fields displays an alert with the error details. The most common cause is a type mismatch, for example, returning text into a Number field.
Formulas must not contain cycles. If field A references field B, and field B references field A, evaluation order is undefined and may produce inconsistent results.
Default values for empty fields
If a field used in your formula has no value, Amazing Fields substitutes a default to keep calculations running. This does not change what is stored in the field, it only affects how the formula evaluates.
| Field Type | Default Value |
|---|---|
| Number | 0.0 |
| Text | "" (empty string) |
| Checkbox | False |
| Date | 1/1/1970 00:00:00 |
| Dropdown (single) | "" (empty string) |
| Dropdown (multi) | [] (empty array) |
Tip: Since empty dates default to 1/1/1970, use YEAR(DateField) > 1970 to check whether a date field has actually been set when checking for empty dates.
For more on how to use formulas for your use case, see a complete list of supported formulas.