Dates and time
Excel serial date converter
Convert Excel serial numbers and dates using the explicit 1900 or 1904 system, including fractional days and Excel’s serial-60 exception.
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Your result
How to use this tool
Select the date system used by your workbook, then choose a conversion direction. Fractional serial values represent the time of day: .5 is noon. No workbook is uploaded and no time zone is inferred.
The 1900 system includes a fictitious 29 February 1900 at serial 60. This tool explains that exception instead of producing a false Gregorian date. Supported dates start at 1900-01-01 in the 1900 system or 1904-01-01 in the 1904 system and end in year 9999. Times resolve to milliseconds.
Worked example
1900 system: serial 59 → 1900-02-28; serial 61 → 1900-03-01. The same Gregorian date has serials 1,462 apart between the two systems.
References and method
Contifield is an independent utility site. Reference publishers do not endorse this tool.
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