Formula fields in SignNow let you compute values automatically based on other fields in your document. Instead of asking signers (or your team) to do math, you define a formula and the result fills in instantly — perfect for invoices, quotes, order forms, timesheets (hours × rate), or expense reports (line-item sums).

Here’s how it works: place a Formula field where the result should appear, then build an expression that references other fields (e.g., Subtotal + Tax - Discount, or Hours * Rate). As signers enter data, the formula updates live. The result is read-only, ensuring consistent totals and audit-ready accuracy.

You can format the result (e.g., decimals, currency style) to match your document. For best results, make critical inputs required, and preview the document to confirm that the calculation behaves as expected. Formula fields reduce back-and-forth, prevent manual errors, and speed up completion.

Before adding the Formula field, first add the fields the calculation will reference. You can use Text field/-s with numerical or currency validation, Number field/-s, Currency field/-s or Dropdown field/-s. Validation is set in the right-side settings panel (note: the Dropdown does not have a validation setting).

Optionally, give the field a Unique Field Name to assign a unique ID that will be used in the formula.

Configure the Dropdown field the same way. Select a Dropdown from the left-side tab and place it on the document. In the right-side settings' tab, set the values you want to appear — numbers only — and ensure the Add "Other" Option checkbox is disabled.

When you’ve finished adding fillable fields, select the Formula field, place it on the form, and build your expression in the pop-up. Reference Text, Number, Currency and Dropdown fields by typing their Unique Field Name in curly brackets (e.g., {subtotal}). Formulas work with fields that have numeric validation. Type { to insert a field from the list, and use + - * / ( ) and numbers to create the formula.

Formulas support addition, subtraction, multiplication, and division, and you can round the result to a set number of decimal places. You can also attach a Request Payment to the Formula field to charge the calculated amount during signing.