MMDDJJJJ

MMDDJJJJ is a fixed-width date notation that encodes a calendar date by combining two-digit month (MM), two-digit day (DD), and a four-digit year (JJJJ). It is not a formal international standard, but it has appeared in various legacy data formats, file naming schemes, and business systems where dates were stored as an eight-character string without separators.

In this format, examples include 07252023 for July 25, 2023 and 01012000 for January 1, 2000. Because the year is expressed with four digits, MMDDJJJJ can disambiguate centuries more clearly than two-digit-year schemes, provided the data preserves the full year value. The pattern is often used in contexts that favor compact, human-readable codes, such as internal identifiers, batch or lot numbers, or simple date stamps in filenames.

Parsing and validation considerations include checking that MM is between 01 and 12, that DD is valid for the given month and year (including February in leap years), and that JJJJ is a plausible four-digit year. Since there are no universal separators, automated validation typically relies on fixed-position parsing or explicit metadata describing the field lengths. When exchanging data with other systems, MMDDJJJJ may be less portable than standardized formats like ISO 8601 (YYYY-MM-DD) or MM-DD-YYYY, which offer broader interoperability and consistent lexical ordering.

Variants and related formats include MMDDYYYY, MM-DD-YYYY, and YYYYMMDD. The choice of format often depends on historical conventions, system constraints, or the need for fixed-width, separator-free representations. See also ISO 8601 and fixed-width date encodings.