Formula fields combined with Flow
Key Takeaway
A cross-object formula field calculates a value from fields on a record and its parent record and shows it on the page layout. A record-triggered flow is the tool for sending an email automatically when a record reaches a given state.
A formula calculates a value from other fields, expressions, or values. Admins use formulas in two places that often work together. A formula field on an object calculates a field value automatically. A flow formula inside a flow does calculations and drives decisions while the flow runs. The two follow mostly the same syntax, but they handle blanks, errors, and some functions differently. In a business scenario, your job is to match each need to the right tool or to a combination of tools.
Formula fields
A formula field uses a formula to calculate a field's value automatically from other fields. Formula fields are available in all editions, in both Salesforce Classic and Lightning Experience.
You build a formula field the same way you create any custom field. Then you pick a data type that matches the output of your calculation. To create, change, or delete formula fields, you need the "Customize Application" permission.
Like other fields, a formula field belongs to an object. You set its field-level security and choose the page layouts that display it, so users see the calculated value on the record page.
If the formula references number, currency, or percent fields, you choose how it handles blanks. The options are "Treat blank fields as zeros" and "Treat blank fields as blanks".
Formula fields and flow formulas can each contain up to 3,900 characters, including spaces, return characters, and comments. If a formula field needs more, create separate formula fields and reference them in another formula field. After it evaluates, a formula field displays at most 1,300 characters.