Format Listing

Notes:

• This table is not exhaustive.
• This page targets ISO 8601-1:2019. Previous editions and drafts contain key differences.
• ISO 8601-2:2019 contains additional representations including sub-year groupings (e.g. for seasons); grouped units; sets; uncertainty qualifications; and date arithmetic. These are not yet represented on this page.
• RFC 3339 suggests other characters could be specified to replace the T in downstream standards but only gives a space character as an example.
• RFC 3339 is case-insensitive so every T or Z could also be t or z respectively. Previous editions of ISO 8601 were also case-insensitive.
• ISO 8601 allows decimal fractions of the smallest time value. These are mostly represented here by a single fractional digit but the standard allows arbitrary precision.
• ISO 8601 allows commas and dots for decimal separation but they are interchangeable in all formats.
• ISO 8601 uses a hyphen character (in Unicode, U+2010 HYPHEN "‐") and minus character (in Unicode, U+2212 MINUS "−").
  When using character sets which don't have these characters a hyphen-minus character (in Unicode, U+2D HYPHEN-MINUS "-") should be used instead.
  The formatter defaults to using hyphen-minus which is valid under both standards.
• ISO 8601-1:2019 permits omitting the T in the time of day representations (Times) when unambiguous.
  However, a T is always required in date and time of day representations (Date-Times).
  Previous editions also allowed omitting the T in Date-Times but it was never permitted to insert alternative characters (e.g. space or underscore).
• The format key is given below the table.

Format Key

%L - Millennium
%C - Century
%X - Decade
%Y - Year
%M - Month
%D - Day
%V - Week Year
%W - Week
%w - Week Day
%O - Ordinal Day
%h - Hour
%m - Minute
%s - Second
%u - Microsecond
%Z - Zone Hour including +/-
%z - Zone Minute
%[,.]3x - Value including fraction with given precision, using either comma or dot.
%−Z     - Use U+2212 for negative timezone hours (ISO recommended)