Excel Date Converter
Convert between Excel serial dates and standard date/time formats easily.Conversion Direction
Date System
Excel Serial Number
How to Use
- 1Select the conversion direction: 'Serial → Date' to decode an Excel serial number, or 'Date → Serial' to get the Excel number for a date.
- 2For Serial → Date: enter the Excel serial number (e.g. 45200) and select the date system (1900 or 1904), then click Convert.
- 3For Date → Serial: pick the date/time from the picker and select the date system, then click Convert.
- 4The result shows the Excel serial number, UTC time, and local time. Use copy buttons to copy any value.
- 5Excel for Windows uses the 1900 system; Excel for Mac (older versions) uses the 1904 system.
About Excel Date Serial Numbers
The 1900 Date System
Excel's default date system counts days from January 0, 1900 (i.e., December 31, 1899 = 1). Day 1 = January 1, 1900. Note: Excel incorrectly treats 1900 as a leap year (serial 60 = Feb 29, 1900 which never existed), a legacy bug from Lotus 1-2-3 compatibility.
The 1904 Date System
The 1904 date system was introduced for older Excel for Mac versions and counts from January 1, 1904. When sharing files between Windows and Mac Excel, dates may appear shifted by 1,462 days (4 years + 1 day) if the systems differ.
Practical Uses
Excel serial numbers are useful for date arithmetic directly in spreadsheets — subtracting two dates gives the number of days between them. They are also used when importing/exporting data between Excel and databases, and for inter-system date conversion.