Microsoft Office

Working with Dates
and Times
Beginners often find that working with dates and times in Excel can be
frustrating. To work with dates and times, you need a good understanding
of how Excel handles time-based information. This chapter provides the
information you need to create powerful formulas that manipulate dates and
times.
The dates in this chapter correspond to the United States English
date format: month/day/year. For example, the date 3/1/1952
refers to March 1, 1952, not January 3, 1952. I realize that this setup may seem
illogical, but that’s the way Americans have been trained. I trust that the non-
American readers of this book can make the adjustment.
NOTE
IN THIS CHAPTER
An overview of using dates and
times in Excel
Excel’s date-related functions
Excel’s time-related functions
How Excel Handles Dates and Times
This section presents a quick overview of how Excel deals with dates and times.
It includes coverage of the Excel program’s date and time serial number system,
and it offers tips for entering and formatting dates and times.
Understanding date serial numbers
To Excel, a date is simply a number. More precisely, a date is a serial number that
represents the number of days since the fictitious date of January 0, 1900. A
serial number of 1 corresponds to January 1, 1900; a serial number of 2 corresponds
to January 2, 1900, and so on. This system makes it possible to deal with
dates in formulas. For example, you can create a formula to calculate the number
of days between two dates (just subtract one from the other).
Excel support dates from January 1, 1900, through December 31, 9999 (serial
number = 2,958,465).
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