YYYY-MM-DD

Units & Measurements abbreviation · Time

YYYY-MM-DD stands for Year-month-day (ISO 8601 date format), a time abbreviation.

The international standard date order defined in ISO 8601, running from the largest unit to the smallest: 2026-11-04. Dates in this form sort correctly as plain text, which makes it the default in databases, logs and many national standards.

Example: Use the YYYY-MM-DD format in file names, such as 2026-11-04_report.pdf, so they sort in date order.

Usage notes

Year-first dates are everyday usage in China, Japan, Korea, Hungary, Lithuania and Sweden. The format avoids the MM/DD versus DD/MM ambiguity entirely, which is why scientific data sets and international organizations favor it. Internet protocols use the closely related RFC 3339 profile.

Related abbreviations

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 →

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