One of the most popular Microsoft Excel date functions is the NOW function. The NOW function adds the current date or time to a worksheet and can also calculate a value based on the current date and time and update that value every time you open the Calculation sheet.
The information in this article applies to versions of Excel 2019, 2016, 2013, 2010, and 2007, as well as Excel for Microsoft 365 for Mac and Excel for Mac 2011.
The NOW function syntax has no arguments. Data is entered between the brackets of the function.
Like most Excel functions, the NOW function is entered into a worksheet through the function dialog box. Since no arguments are needed, the function can be entered by typing in the active cell =Now() and press Enter. The result shows the current date and time.
To change the information displayed, use to adjust the cell formatting so that only the date or time is displayed format Tab.
Keyboard shortcuts for formatting date and time
Keyboard shortcuts help you quickly format the output of the NOW function. For the date, enter (date-month-year format). Ctrl+Shift+#. Enter for the time (hour-minute-second and am/pm format). Ctrl+Shift+@.
serial number or date
The reason the NOW function takes no arguments is that the function gets its data by reading the computer’s system clock. Windows versions of Excel store the date as a number representing the number of full days since midnight January 1, 1900, plus the number of hours, minutes, and seconds for the current day. This number is called serial number or serial number.
Since the serial number continuously increases with each second, entering the current date or time with the NOW function means that the output of the function changes continuously.
Volatile Functions
The NOW function is part of the Excel family of volatile functions that recalculate or update when the worksheet they are in is recalculated, just like SUM and OFFSET.
For example, spreadsheets are recalculated each time they are opened or when certain events occur, e.g. For example, when you enter or edit data that causes the date or time to change, unless automatic recalculation is turned off.
To force the feature update at any time, press changeF9 to recalculate the active or current worksheet, or press F9 to recalculate all open workbooks.