Excel Date
Decode Excel serial date numbers into ISO and local dates, or turn a date into the serial number Excel expects. Handles the 1900 leap-year bug and the 1904 date system.
Frequently asked questions
- Why is my date off by one day?
- Excel treats 1900 as a leap year even though it was not, so serials before 1 March 1900 need special handling; the tool accounts for it.
- What is the 1904 system?
- Older Mac Excel files count days from 1904-01-01; switch the system to convert those files.