The Days360 function in Excel is a useful tool for calculating the number of days between two dates, with a few key differences from the standard DATEDIF function. While the DATEDIF function calculates the number of days based on the actual number of days between two dates, the Days360 function calculates the number of days based on a 360-day year. This can be useful in certain financial and business contexts, where a year is often assumed to have 360 days for the purpose of calculating interest or other financial transactions.

To use the Days360 function in Excel, you will need to enter the function into a cell and provide two arguments: the start date and the end date. You can enter these arguments as cell references or as literal dates in the form of “dd/mm/yyyy”. For example, to calculate the number of days between January 1, 2020 and March 31, 2020, you could use the following formula:

=DAYS360(“01/01/2020”, “03/31/2020”)

This would return the result of 90, since there are 90 days in the three months between January and March.

There are a few additional options that you can use with the Days360 function to customize the calculation. These options include:

- End_of_month: This optional argument allows you to specify whether the end date should be considered as the end of the month (TRUE) or the last day of the month (FALSE). If you set this argument to TRUE, the function will assume that the end date is the last day of the month, even if it falls on a different day. For example, if the end date is March 15, the function will assume that it is the end of March and will include the entire month in the calculation.
- European: This optional argument allows you to specify whether the calculation should use the European method of calculating days (TRUE) or the US method (FALSE). The European method assumes that a month has 30 days, regardless of the actual number of days in the month. This means that the number of days between two dates will always be a multiple of 30. The US method, on the other hand, calculates the number of days based on the actual number of days in each month. For example, if the end date is March 31, the US method would include the entire month in the calculation, while the European method would only include 30 days.

To use these optional arguments, you would simply add them to the formula as additional arguments, separated by commas. For example, to calculate the number of days between January 1, 2020 and March 31, 2020 using the European method and considering the end date as the end of the month, you could use the following formula:

=DAYS360(“01/01/2020”, “03/31/2020”, TRUE, TRUE)

This would return the result of 120, since there are 120 days in the three months between January and March using the European method.

There are a few things to keep in mind when using the Days360 function in Excel. First, it is important to note that the function only calculates the number of days between two dates, not the number of months or years. If you need to calculate the number of months or years between two dates, you will need to use a different function, such as DATEDIF or MONTHS.