Date and Time

How do Dates and Times work in Excel

In Excel, dates and times are considered as numbers : the date 0 is the first of January 1990, and each day since is 1. Therefore, the 16th of May 2014 is 41775, number of days since the 1st of January 1900.

In the same way, times are also considered as numbers. 24h equals 1. So, when it's midday, the time is equal to 0.5.

The cell containing a date or a time has to be in the correct "date & time" cell format

Considering date and times as numbers allows you to make standard operations with them : add, divide, average, etc.

For example :

How to use date & time functions in Excel

There are number of pre-programmed functions in Excel, to manipulate dates and times functions. (This is a true Excel file, please handle it!)

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The date and time functions

You will see by clicking on the "start" button that there is some date and time functions. The most usefull are :

Some tips