--- title: FORM Butler – Formula Form Field description: Formula Form Fields allow you to perform automatic mathematical calculations directly inside a PDF Form. As users enter values into Number or Currency fields, the calculated field is updated immediately without requiring any manual intervention. The calculated value is displayed… url: "https://pdfbutler.com/academy/form-butler-academy/form-butler/using-formula-form-fields-in-pdf-forms/" updated: "2026-09-28" category: FORM BUTLER --- # FORM Butler – Formula Form Field Formula Form Fields allow you to perform automatic mathematical calculations directly inside a PDF Form. As users enter values into Number or Currency fields, the calculated field is updated immediately without requiring any manual intervention. The calculated value is displayed in a read-only field and is intended for display purposes only. It is not written back to Salesforce. > NOTE: **Formula Form Fields only work with Single Form Field or other Formula Form Fields.** --- #### Before You Begin Formula Form Fields are designed to work with PDF Forms created using Form Butler. You can use this article on how to setup and generate Forms: [End-2-End Setup and Demo](https://pdfbutler.com/academy/form-butler-academy/form-butler/end-2-end-setup-and-demo-2/) --- #### Choosing the Correct Form Field Type PDF Butler provides two different Config Types for working with numeric values in PDF Forms. Although they may appear similar, they serve different purposes. ##### Single Form Field Use a **Single Form Field** when you want the recipient of the Form Request to **enter or edit** a value. For Example: Quantity Users can change these values while completing the form, and any Formula Form Fields that reference them are recalculated automatically. > **Note:** Single Form Fields support **numeric values only**. They do not provide currency formatting. > ![](https://pdfbutler.com/wp-content/uploads/2026/09/Screenshot-2026-09-15-at-14.06.29-300x292.png) > > > > ![](https://pdfbutler.com/wp-content/uploads/2026/09/Screenshot-2026-09-15-at-14.06.49-300x289.png) ##### Formula Form Field Use a **Formula Form Field** when you want PDF Butler to **calculate a value automatically**. Unlike a Single Form Field, this field is **read-only** Formula Form Fields are ideal for calculated values such as: - Unit Price - Line Total - Tax Amount - Grand Total - Discounts - Subtotals A Formula Form Field can be configured as either: - **Number** – displays the result as a numeric value. - **Currency** – formats the calculated value as a currency. ![](https://pdfbutler.com/wp-content/uploads/2026/09/Screenshot-2026-09-15-at-14.08.56-300x150.png) Use the **Currency** option whenever the calculated result represents a monetary value. > **Tip:** If you want to display a Salesforce Currency field (such as **Unit Price**) in your PDF, you can use a **Formula Form Field** even if **no** **calculation** is required. Adding a formula is only necessary when you want the value to be calculated dynamically. > ![](https://pdfbutler.com/wp-content/uploads/2026/09/Screenshot-2026-09-15-at-14.09.15-300x254.png) --- #### Supported Operations Formula Form Fields support the following mathematical operations: | Operation | Symbol | Example | | --- | --- | --- | | Addition | + | `[[!Price!]] + [[!Tax!]]` | | Subtraction | - | `[[!Amount!]] - [[!Discount!]]` | | Multiplication | * | `[[!Qty!]] * [[!UnitPrice!]]` | | Division | / | `[[!Total!]] / [[!Items!]]` | | Parentheses | ( ) | `([[!A!]] + [[!B!]]) * [[!C!]]` | | SUM Function | SUM() | `SUM([[!NetTotal!]])` |   --- #### Configuring a Formula Form Field ##### Configure the Input Fields Create the fields that users will complete in the PDF. For example: Qty and UnitPrice These fields must use either: - **Number** validation - **Currency** validation ##### Add a Formula Form Field Create a new Config Type using: **FORMULA_FOR_FORM_FIELD** This field will display the calculated result. Unlike other Form Fields, this field: - is automatically populated - cannot be edited by the user - recalculates whenever one of the referenced fields changes ##### Enter the Formula Use merge fields to reference the input values. Example: ``` [[!Qty!]] * [[!UnitPrice!]] ``` ![](https://pdfbutler.com/wp-content/uploads/2026/09/Screenshot-2026-09-15-at-14.10.52-300x286.png) ##### Using Multiple Operations You can combine several mathematical operators in a single expression. Example: ``` [[!Qty!]] * [[!UnitPrice!]] / 100 ``` Or use parentheses: ``` ([[!Price!]] + [[!Tax!]]) * [[!Quantity!]] ``` The calculation is evaluated using the normal mathematical precedence rules. ##### Calculating Grand Totals with SUM() The SUM() function allows you to total values from all matching fields in the PDF. Example: ``` SUM([[!NetTotal!]]) ``` ![](https://pdfbutler.com/wp-content/uploads/2026/09/Screenshot-2026-09-15-at-14.23.13-300x168.png) Instead of calculating only a single row, PDF Butler finds every field named **NetTotal** and adds their values together. This is especially useful for: - invoices - quotations - order forms - product lists **Note:** The SUM() function accepts only one merge field. Correct: ``` SUM([[!NetTotal!]]) ``` Not supported: ``` SUM([[!Qty!]] * [[!Price!]]) ``` --- #### Important Notes - Formula Form Fields are **read-only** and cannot be edited by end users. - Formula values are calculated only inside the generated PDF. - Calculated values are **not written back to Salesforce**. - Formulas are recalculated every time a referenced field changes. - **SUM() formulas are evaluated after all other formulas** to ensure accurate totals. Please note the following limitations: - **Formula Form Fields only work with Single Form Field or other Formula Form Fields.** - **Only fields using Number or Currency validation are processed.** - Text, Date, Checkbox, Picklist, Signature, and other field types are not supported. - Only the following operators are supported: - Addition (+) - Subtraction (-) - Multiplication (*) - Division (/) - Parentheses ( ) - SUM()