What is YYDDD?
YYDDD uses the last two digits of the year followed by the day number within the year.
Example: the 152nd day of 2025 becomes 25152.
Julian Date Converter
Julian Date Converter
Convert Gregorian, YYDDD and CYYDDD dates instantly.
Built for quick checks, spreadsheets, data work and operational systems.
Converter
Results
YYDDD
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CYYDDD
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YYDDD = 2-digit year + day of year •
CYYDDD = century + 2-digit year + day of year
What is CYYDDD?
CYYDDD adds a century digit before the year and day number.
Example: 125152 means century 1, year 25, day 152.
Fast by design
JulianDate.net is built as a lightweight utility: fast loading, no account required, and focused on getting the right date value quickly.
Bulk Converter
Paste multiple dates or Julian values, convert them in one batch, and copy the results straight back into Excel, ERP sheets or data tools.
One value per line. Empty lines are ignored.
Results are returned one per line, ready to paste into spreadsheets.
Ready
Excel Formulas
A dedicated formulas section is planned next with copy/paste Excel examples for Gregorian to YYDDD, Gregorian to CYYDDD, and Julian date back to calendar date.
API-ready
Future versions can include lightweight JSON endpoints for websites, intranets, dashboards and data tools.
Copy-first workflow
The Bulk Converter is designed for office users who need to paste large data sets, convert them quickly, and copy the output back into their own sheets.