A method, system, and computer-readable medium are provided for controlling the calculation of volatile functions in a workbook created in a spreadsheet application program such that the volatile function does not need to be recalculated each time a calculation request is received in the workbook. A volatile function may include a function which is capable of returning a different value each time the function is calculated. The spreadsheet application program determines a calculation mode setting for the workbook, calculates a volatile function timeout value based on the calculation mode setting, and calculates the volatile function based on the volatile function timeout value. The volatile function timeout value may include a time span for which the results of a volatile function are valid. The volatile function timeout value is calculated by determining the maximum of a workbook timeout value assigned to the workbook on a client computer and a server timeout value assigned to the workbook on a server computer running the spreadsheet application program. During the volatile function timeout period, the volatile functions are not recalculated.