Calculator Field

Introduction
Calculator Field lets site builders compute values from other fields using a simple tokenized math formula (e.g., “[field_price] * [field_quantity]”), with live updates on edit forms and computed output on view.

Features

Build formulas with field tokens: “[field_a] + ([field_b] * 0.2)”
Live calculation on node edit forms (no save required)
Formatter computes at view time (server-side) for accurate output
Optional display of:
Original formula
Formula with current field values substituted (e.g., “10.50 * 3”)
List of fields used and their values
Token picker for eligible fields (integer, float, decimal), excludes system fields

Post-Installation

Structure → Content types → Manage fields → Add “Calculator Field”
Structure → Content types → Manage form display → Edit “Calculator Widget”
Enter formula using tokens (click tokens to insert)
Structure → Content types → Manage display → Choose “Calculator Formatter”
Optional: enable “Show formula” and “Show formula with values”
Optional: add custom CSS classes
Clear caches if needed (drush cr)

Additional Requirements

Drupal core 10 or 11
Token module
Composer: composer require drupal/token

Recommended modules/libraries

None required. If you need stricter evaluation, consider a PHP math parser library to replace eval-based evaluation.

Similar projects

Computed/Calculated field modules. Calculator Field focuses on:
Simple, token-based formulas
Live JS updates on edit forms
On-the-fly, server-side computation via the formatter
Clean UI with token picker and optional formula displays

Supporting this Module

Contributions, issues, and feature requests are welcome on the project issue queue.

Community Documentation

Add tutorials, walkthroughs, or demo links here.