Excel Date Converter
Convert between Excel serial date numbers and calendar dates. Excel stores dates as sequential serial numbers for calculations.
Integer part = date, decimal part = time (0.5 = 12:00 noon)
Result
12/30/1899 12:00:00 AM
ISO: 1899-12-29T18:38:50.000Z
Day: Saturday
Year: 1899
Month: 12
Day: 30
Hour: 0
Minute: 0
Second: 0
About Excel Dates
Excel uses serial numbers to store dates. In the 1900 system (Windows), day 1 is January 1, 1900. In the 1904 system (Mac), day 0 is January 1, 1904.
Note: The 1900 system has a known bug where it incorrectly treats 1900 as a leap year (inherited from Lotus 1-2-3). February 29, 1900 is day 60, but this date never existed.