Specify Calculation dialog box
This dialog box appears so that you can build a formula for a calculation or calculated field.
If necessary, for Evaluate this calculation from the context of, choose a table from the list.
Setting the context for a calculation is only necessary when you're creating a calculation field in a source table that has two or more occurrences in the relationships graph. The choice you make may affect the calculation results, particularly if your calculation will include fields in related tables.
For more information on the use of context in calculations, see Choosing the evaluation context for a calculation field.
Click where you want the item to appear in the formula box, then do the following. (You can also type the formula into the box.)
Note  When the Specify Calculation dialog box opens from within the Replace Field Contents and Send Mail dialog boxes, the tables list may default to Current Layout (LayoutName) and display only the visible fields on the current layout. To display all field names from the current table, choose Current Table (TableName) from the list.
For Operators, click a button or type an operator. See Mathematical operators and Text operators.
For Operators, double-click an operator in the list or type an operator. See Comparison operators and Logical operators.
Constant value
To quickly build a formula:
Choose a data type for Calculation result is <value>.
Select Number of repetitions, then type the number of repetitions. See Defining repeating fields.
Select Do not evaluate if all referenced fields are empty.
To select indexing and storage options for the field, click Storage Options, select options in the Storage Options dialog box, then click OK.
See Defining field indexing options and Defining global fields (fields with global storage).
Important  To avoid confusion when using dates in FileMaker Pro, always define calculation formulas to enter four-digit years. See Conversion of dates with two-digit years.
If you are using FileMaker Pro Advanced to customize menus, you can base a menu or menu item title on the result of a calculation. You can also create tooltips based on a calculation. See Defining custom menus (FileMaker Pro Advanced) and Adding tooltips on layouts.
Related topics 
About functions
About formulas
Adding a new line to the results of a formula
Adding comments to a formula
Changing calculation formulas
Defining calculation fields
Defining automatic data entry
Defining field validation
Defining field indexing options