Excel serial date to real date
For example, 45261 is Fri, Dec 01, 2023, 12:00:00 AM UTC, which is 2023-12-01T00:00:00.000Z in ISO 8601 and 1701388800 in Unix seconds.
Day count in Excel's 1900 date system, where serial 1 is January 1, 1900. The fraction is the time of day, read as UTC.
Detected: Excel serial date/t/45261
Your timezone
UTC · GMT+00:00 · UTC
Fri, Dec 01, 2023, 12:00:00 AM
Common formats
UTC
Fri, Dec 01, 2023, 12:00:00 AM
ISO 8601
2023-12-01T00:00:00.000Z
Unix (seconds)
1701388800
Unix (millis)
1701388800000
Relative
…
Excel stores dates as serial numbers: days since its 1900 epoch, with the time of day as a fraction. 45261.75 is December 1, 2023 at 18:00. If a spreadsheet ever handed you a five-digit number where a date should be, that's what it is. Paste one below to convert it, fraction and all. One quirk to know: Excel counts a February 29, 1900 that never existed, so its serials below 61 sit one day off the real calendar. This page shows the date Excel displays for each serial and flags serial 60 as the phantom day. The same encoding appears as OADate in .NET and in many CSV exports.
Do it with the API
curl https://parsetime.dev/api/t/45261?format=excelThe same conversion as JSON: no key, no signup, permissive CORS. Try this call or read the API docs.
Common questions
- Why does Excel show a number like 45261 instead of a date?
- The cell is formatted as a number rather than a date, but the underlying value is the same either way: days since the 1900 epoch. Paste the number above to see which date it is, or reformat the cell in Excel.
- How do I convert an Excel serial number to a date by formula?
- In Excel itself, just format the cell as a date. To do it arithmetically: the Unix timestamp is (serial − 25569) × 86400, because 25569 is the serial for January 1, 1970.
- What is the 1900 leap-year bug?
- Excel treats 1900 as a leap year to stay compatible with Lotus 1-2-3, so it counts a February 29, 1900 that never existed. Serial 60 is that phantom day, and serials 1 to 59 sit one day off the real calendar. This converter shows the date Excel itself displays for each of them and flags serial 60. From serial 61, March 1, 1900, the numbers line up with the real calendar.
- What about the 1904 date system?
- Old Mac versions of Excel counted from January 1, 1904 instead. If a converted date is exactly 1,462 days off, the file uses the 1904 system. Add 1462 to the serial and convert again.