You can use the formula field to construct simple equations using eligible fields in a process. It can also be used to calculate data using dates. 

The example below is a simple invoice process that includes a money, quantity, and percent field types. In this process the formula field is used to calculate the Total Cost($). 

To use the formula field, drag the Formula field into the Fields template. 

Name the Field. You have to option to make the formula span one or two columns. 

Choose the Format you want the formula's product to display. You can choose from Number or Date. 

The Duration format type will display a list of Eligible units you can choose to display the duration amount.

Click into the fx formula section to to start adding fields to you formula. You can add basic Operators to your formula field as well as parentheses to create your formula. 

The Date format type will convert the formula you've created into a date value. As an example, you can create date formulas to calculate the date 30 days from an initial date field. 

Date and Time fields are brought into the formula as a value that is calculated based on the number of seconds since midnight of Jan 1, 1970. There will be a help icon next to the radio buttons that will provide you with a table that will list out the number of seconds in an hour, day, week, etc. to save you a bit of time from having to calculate these numbers yourself.

To calculate 30 days from a certain date, you can either add the number of seconds in a month (30days) or add the number of seconds in a day and then multiply it by 30 as shown in my example below.

Both will result in the same value. 

Table Field Formulas

Depending on which table fields you select to add to your formula or if the formula is in or outside of the table will determine the calculated value. There will be a Table field help icon that will display the formula outcome based on the input values from the table. 

Formula Fields In a Table field

To use a formula field in a table, click and drag the Formula field into place on the table. 

Name the field and choose the format you want the formula's product to display as. Add fields to the Formula fx by selecting the field and operators from the drop down list. Fields that belong to a table field will be displayed under the name of the table field.

Adding fields to a formula that belong to a table field will be displayed with the table name followed by the field name. 

Formulas Not in a Table Field

In this example, you can calculate the Average Cost of the Total Cost ($) based on the number of rows entries added to a Table.

Adding a formula field type to the formula will sum the total of the Total Cost column and adding the Table Formula field will sum the number of rows added to the table field.