This Excel date converter translates between the serial numbers that spreadsheets use and ordinary calendar dates. Excel and other spreadsheets store dates as a count of days, so a date you see as a normal date is really a number underneath. This tool shows you both sides.
For example, the serial number 46247 is August 13, 2026.
How the Excel Date System Works
In the standard spreadsheet date system, day number 1 is the first of January 1900. Every later date is the number of days since then, so dates can be added and subtracted like plain numbers. The time of day is stored as the fractional part, where a half day is 0.5.
When to Convert Serial Numbers
Sometimes a spreadsheet shows a bare number where you expected a date, usually because the cell format was lost during an export or an import. Pasting that number here gives you the real date. Going the other way, you can find the serial number for a date when you need to build a formula or a fixed value.
A Note on the 1900 Leap Year Quirk
Spreadsheets treat the year 1900 as a leap year even though it was not, which adds one phantom day in early 1900. This only affects dates before the first of March 1900, which almost never appear in real data. For every modern date the conversion is exact.
What People Use It For
- Fixing dates that show as numbers after an export
- Building spreadsheet formulas that need a serial value
- Checking how a spreadsheet stored a particular date
- Moving date data between tools and systems