What Does YYYY-MM-DD Mean?
Example: 2025-12-31
Understanding YYYY-MM-DD
ISO 8601 standard format, ideal for sorting and international use
YYYY
Year (4 digits)
e.g., 2026
MM
Month (2 digits)
01-12
DD
Day (2 digits)
01-31
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-DD, 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-DD | Breakdown |
|---|---|---|
| New Year's Day | 2026-01-01 | 2026 / 01 / 01 |
| Valentine's Day | 2026-02-14 | 2026 / 02 / 14 |
| Independence Day (US) | 2026-07-04 | 2026 / 07 / 04 |
| Christmas | 2026-12-25 | 2026 / 12 / 25 |
| New Year's Eve | 2026-12-31 | 2026 / 12 / 31 |
Common Confusion
Watch out! A date like 03/04/2026 can be confusing:
- In MM/DD/YYYY (US): This is March 4, 2026
- In DD/MM/YYYY (EU): This is April 3, 2026
To avoid confusion, consider using YYYY-MM-DD (ISO 8601) which is unambiguous.
Related Pages
Frequently Asked Questions
What does YYYY-MM-DD stand for?
YYYY-MM-DD 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.