Serial date
A date stored as a count of days from a fixed starting date, which is how a spreadsheet keeps dates internally. The number 45000 is a day in March 2023 under the most common starting date.
The number appears when a date cell loses its date formatting or is exported as a plain value. Converting it back requires knowing the starting date, because more than one is in use and they differ by several years.
Where it comes up
- Dates stored as serial numbersA date appears as a plain number, such as 45292, because it was exported as a count of days or seconds instead of as a calendar date.
- Mixed date formatsOne column holds dates written in several different styles.
See also
- TimestampA value that records a date and a time of day together, marking one moment: 2025-03-04T14:30:00Z.
- ISO 8601The international standard for writing dates and times, year first: 2025-03-04 for the fourth of March 2025.
- SpreadsheetA program, or a file made with one, that arranges values in a grid of cells where any cell can hold any kind of value or a formula.