What Does YYYY-MM Mean?
Example: 2025-12
Understanding YYYY-MM
Year-month format following ISO 8601, ideal for file naming and sorting
YYYY
Year (4 digits)
e.g., 2026
MM
Month (2 digits)
01-12
What Each Letter Means
| Symbol | Meaning | Example |
|---|---|---|
| Y | Year digit | YYYY = 2026, YY = 26 |
| M | Month | MM = 02, M = 2, MMM = Feb, MMMM = February |
| D | Day of month | DD = 03, D = 3 |
Tip: Uppercase letters (MM, DD) usually mean zero-padded numbers (01, 02, 03). Lowercase or single letters (M, D) may mean no padding (1, 2, 3).
About the Separator
In YYYY-MM, the separator between date parts is: -
| Separator | Format Example | Common Usage |
|---|---|---|
| / | MM/DD/YYYY | US, UK dates |
| - | YYYY-MM-DD | ISO standard, databases |
| . | DD.MM.YYYY | Germany, Russia |
Real-World Examples
| Date | YYYY-MM | Format Breakdown |
|---|---|---|
| New Year's Day | 2026-01 | 2026 / 01 |
| Valentine's Day | 2026-02 | 2026 / 02 |
| Independence Day (US) | 2026-07 | 2026 / 07 |
| Christmas | 2026-12 | 2026 / 12 |
| New Year's Eve | 2026-12 | 2026 / 12 |
Related Pages
Frequently Asked Questions
What does YYYY-MM stand for?
YYYY-MM is a date format pattern where each letter represents a part of the date: Y = Year, M = Month, D = Day. The number of letters indicates the format (YYYY = 4-digit year, MM = 2-digit month with leading zero).
Why do some formats use uppercase and some lowercase?
In most systems, uppercase letters like MM and DD represent zero-padded values (01, 02, 03), while lowercase or single letters may represent non-padded values (1, 2, 3). However, this can vary by programming language.