YYYY

Units & Measurements abbreviation · Time

YYYY
Stands forYear (four-digit)
CategoriesUnits & Measurements

YYYY stands for Year (four-digit), a time abbreviation.

Four-digit year placeholder in date formats such as YYYY-MM-DD and MM/DD/YYYY, required on most official forms, databases and travel documents to avoid ambiguity about the century.

Example: Please enter the date as YYYY-MM-DD, for example 2026-11-04.

Usage notes

In Java's SimpleDateFormat and CLDR patterns, yyyy is the calendar year while YYYY is the ISO week-based year; using YYYY by mistake shows the wrong year for dates in the last days of December, a bug that has broken apps around New Year. Moment.js and many form libraries use YYYY for the ordinary year, so conventions depend on the tool.

More time abbreviations

  • a – Annum (year)
  • a.m. – Ante meridiem (before midday)
  • AD – Anno Domini (in the year of the Lord)
  • BC – Before Christ
  • BCE – Before the Common Era
  • BP – Before Present
  • CE – Common Era
  • CY – Calendar year
  • d – Day
  • DD – Day (two-digit, in date formats)
  • DD/MM/YYYY – Day/month/year (date format)
  • FY – Fiscal year

See all 51 time abbreviations →

Edited by the AbbreviationList.com team. Spotted an error or a missing meaning? Contact us.