Introduction to Date and Time Functions

Date and time functions are used when working with date, time, and duration data.

Date and time functions are used when working with date, time, and duration data, and can perform operations like measuring the number of days (DAYS) between two dates, automatically inputting the current date (TODAY) or date and time (NOW), merging multiple values into one date value (DATE), and more.

Date and time functions are used in all sorts of workbooks, from financial applications like Income and Expense Trackers to project management applications like Product Launch Plans all the way to simple To Do Lists.

How to Use Date and Time Functions

In the examples below, we’ll take a look at some commonly used date and time functions. For documentation on every date and time function supported by, reference our section on Date and time functions.

When using functions in your workbook, you can input and edit formulas either directly in the cell, or from the formula bar between the worksheet toolbar and the spreadsheet grid. Learn more in our article on Creating and Editing Formulas.

How to Calculate the Current Date (TODAY) or Date and Time (NOW)

TODAY and NOW are two of the simplest date and time functions. They calculate the current date and date and time, respectively, and require no arguments.


Note that both the TODAY and NOW functions will recalculate whenever your workbook is reloaded. To retain the value at the time the formula is calculated, copy the result, paste it back into the cell, and select “Paste values only” from the paste options dropdown.


How to Calculate the Number of Days Between Two Dates (DAYS)

With the DAYS function, you can easily calculate the difference in days between two dates.


In the example above, we’ve used the DAYS function in Cells C2 and C3 to calculate the number of days between the adjacent start and end dates. Note that the DAYS function works by taking the first argument minus the second argument; if you list the start date as your first argument, the function will return a negative value.

How to Calculate the Number of Working Days Between Two Dates (NETWORKDAYS)

Alternatively, the NETWORKDAYS function can calculate the number of working days between two dates. When calculating duration, NETWORKDAYS automatically excludes weekends and can include an additional argument to exclude other specified holidays.


Note that, because of the difference in function syntax, the order of our arguments has been reversed from the previous DAYS example.

How to Calculate an End Date (WORKDAY)

With the WORKDAY function, you can automatically calculate an end date based on a specified start date and duration, input as a number of workdays.


The WORKDAY function can be especially useful in building out a project management workbook where you’ve estimated approximate durations for each task and want to exclude non-working days from your schedule.

To calculate an end date taking into account all days including weekends and holidays, you can simply calculate the SUM of a start date and duration.

More Date and Time Functions

The functions shown above are just some of the many date and time functions supported by Take a look at our full suite of articles on date and time functions to learn more.

Date and time functions play a key role in project management. Learn more about managing projects with Or, read on to learn more about other types of functions supported by, including statistical functions, math functions, hierarchy functions, and more.