--- schema_version: "1" id: e0e210a05fa5a6b63f865d69f4256eb671c3954b3654db3a2afcc5709763002d title: Using Week-Based Placeholders in Custom Date Formats collection: tableau version: current locale: en-gb portal_url: https://docs.salesforce.com/tableau/current/en-gb/public/desktop/dates_custom_date_formats_week.md canonical_url: https://help.tableau.com/current/public/desktop/en-gb/dates_custom_date_formats_week.htm source_site: help.tableau.com content_type: documentation content_hash: 90db24971b1d32920ef3cb2e27b70ad9559b0960e08742e63498c98def722810 description: Use ISO-8601 week and year placeholders in custom date formats for supported locales. --- [Skip to main content](#main-content) # Format Dates Using ISO-8601 Weeks and Years For many European locales (listed below), Tableau allows you to format dates using ISO-8601 weeks and years. Expand to see European locales that support ISO-8601 in Tableau da-DK, Danish (Denmark) se-SE, Sami, Northern (Sweden) rm-CH, Romansh (Switzerland) sms-FI, Sami, Skolt (Finland) is-IS, Icelandic (Iceland) de-DE, German (Germany) km-KH, Khmer (Cambodia) nl-NL, Dutch (Netherlands) smj-SE, Sami, Lule (Sweden) fi-FI, Finnish (Finland) nn-NO, Norwegian Nynorsk (Norway) it-IT, Italian (Italy) it-CH, Italian (Switzerland) nb-NO, Norwegian Bokmål (Norway) pl-PL, Polish (Poland) sv-SE, Swedish (Sweden) et-EE, Estonian (Estonia) lv-LV, Latvian (Latvia) hsb-DE, Upper Sorbian (Germany) kl-GL, Greenlandic (Greenland) mk-MK, Macedonian (North Macedonia) fo-FO, Faroese (Faroe Islands) se-NO, Sami, Northern (Norway) as-IN, Assamese (India) fy-NL, Frisian (Netherlands) se-FI, Sami, Northern (Finland) ps-AF, Pashto (Afghanistan) prs-AF, Dari (Afghanistan) de-CH, German (Switzerland) sv-FI, Swedish (Finland) dsb-DE, Lower Sorbian (Germany) de-LU, German (Luxembourg) fr-CH, French (Switzerland) smj-NO, Sami, Lule (Norway) de-LI, German (Liechtenstein) sma-NO, Sami, Southern (Norway) sma-SE, Sami, Southern (Sweden) smn-FI, Sami, Inari (Finland) The week and year numbering in an ISO-8601 calendar is different from a standard Gregorian calendar. Here’s how January 2nd, 2011 would be represented:
Calendar SystemWeek NumberYear Number
Standard Gregorian12011
ISO-8601522010
When formatting dates, it’s important to ensure that your month, week and year numbers all come from the same calendar system. Otherwise, the date might not make sense. There are two ways to do this: - Let Tableau guess which calendar system you want to use for each placeholder. For example, if you type `mm yyyy` (a month followed by a year), Tableau uses the standard Gregorian year. In this case, it makes sense to use that year with a month number. - In your format string, place an annotation after each week (ww) or year (yyyy) placeholder, to indicate what kind of placeholder it should be:
AnnotationCalendar to UseExample Format String
[Y]ISO-8601ww[Y] yyyy[Y]
[y]Standard Gregorianww[y] yyyy[y]
Important: To get correct ISO-8601 week numbering, your computer's location must be set to one of the [above](#Expand) locales, and you must set your data source start of week to Monday. (For information on how to do this, see [Date Properties for a Data Source](https://help.tableau.com/current/public/desktop/en-gb/date_properties.htm).) Otherwise, Tableau will number weeks using your data source start of week setting, which may result in partial weeks at the beginning and end of years being created. **Note**: ISO week numbering will not occur if you are using a fiscal year that doesn’t start in January, regardless of the locale you choose. ## Sample format strings for the date December 31, 2013 Here are sample format strings for the date December 31, 2013, where m stands for a month or day-of-month placeholder. Time placeholders, such as hours, minutes and seconds, don’t influence whether or not a year is week-based or year-based.
Format stringFormatted output
yyyy2013
yyyy[Y]2014
yyyy ww2014 1
yyyy mm2013 12
ww yyyy1 2014
mm yyyy12 2013
ww yyyy[y]1 2013
mm yyyy[Y]12 2014
yyyy mm ww2013 12 1
mm yyyy ww12 2013 1
ww mm yyyy1 12 2013
ww mm yyyy[Y]1 12 2014
ww yyyy mm1 2014 12 (format is ambiguous)
ww yyyy[y] mm1 2013 12
ww yyyy mm yyyy1 2014 12 2013
ww yyyy yyyy mm1 2014 2013 12
yyyy mm ww yyyy2013 12 1 2014