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Frequent Visitor

Timeline slicer - ISO week


is there any possibility how to set ISO week date system in Timeline slicer?

For example 2018-12-31 should be W1 (first day of week is Monday).

Thank you,


Regular Visitor

We've implemented the workaround with setting the fiscal year to the 4th of January.
That gives us the right weeks for this year, but that messes up our year (it thinks it's 2022 when you need data over 2021).
Hopefully a fix is in the works

Frequent Visitor

Hi @Wupsje, please check out

They are working on it, although we recently got some radio silence so I have no idea when it will come. I hope they will fix it very soon.


Hi guys,


We are fixing the issue.

ETA is early February.


Kind Regards,


Evgenii Elkin,
Software Engineer
Microsoft Power BI Custom Visuals

Hi @v-evelk ,

Do you have an update for us as it is already April?

Best regards,


Frequent Visitor

Any news on this?

Advocate II
Advocate II

Great to see that there is a larger base that has this issue so maybe it gets pushed forward faster.

As @ora mentioned I logged an issue on the git repository for the visual: Support for custom date hierarchy for year-month-week hierarchy · Issue #74 · microsoft/powerbi-visu...

Frequent Visitor

We need this fixed urgently. The slicer now fools the users that depend on week selection. We use the Timeline Slicer since it is far superior in user-friendliness to other slicing alternatives (especially so when you want to alternate between year/month/week and sometimes day selections).

I wrote this up like an email:


We are unfortunately experiencing a bug with the Timeline Slicer developed by Microsoft. Ref. 

We have the slicer in its latest version (2.1.1). The slicer is not selecting the correct weeks for us. It seems to have a built in function to give week numbers based on the US ordering of weeks, and not the standard ISO weeks which is used in Europe.

Take the year 2017 as an example. The slicer shows 53 weeks there (since in the US, when 2017 starts its week 1 with the Sunday, 2017 ends up with 53 weeks), while the ISO week calendar only has 52 weeks in 2017. We had previously assumed it to support ISO-weeks when it let us select start of the week = “Monday”, but have now discovered there is no ISO-week logic in this slicer.

Will this slicer offer support for ISO weeks in the future?

We need it urgently fixed if possible, since we do not really have a good date slicing alternative in Power BI. Please let us know if it is possible to get faster resolution if we participate in some fashion. Could you suggest alternatives if it is not possible to get a quick fix? This slicer is a core component of our reports, and the default slicer cannot be compared in terms of user-friendliness.

Please see the image below that illustrates this. To recreate this, simply use a date dimension built with iso week numbers, and let date fill the timeline slicer. In this example, I expected the same days selected when I click “W1” in the slicer, and not “W2”. This is why I also show the weeks below.

timeline slicer isoweek.png

("Mandag" = Monday, "Første dag i uken" = first day of week)

My interpretation is that this issue occurs for all years where january 1st is a friday, saturday or sunday, since the week numbering rules are then different. I.e. 3/7 (43%) of all years are displayed incorrectly for us in this slicer.

@v-viig could you please give us an update?

Hi ora,


I was contacted by a MS Software Developer and asked for a sample repo.

So I sent him a minimized sample repo which includes my custom date table and Time Slicer Visual in two flavors.

Week Start is set to Monday on both of them.

On the left Fiscal Year Start is set to 1st Jan:

Time Slicer left.jpg

On the right Fiscal Year Start is set to 4th Jan:

Time Slicer right.jpg

Hopefully we get a fixed version, soon! 😉


Best regards


Advocate I
Advocate I


I think it's because the American method of week numbering differs from the ISO / European week numbering method. We over here in Europe, usually use Monday as the start of the week and in case January 1 is on Monday, Tuesday, Wednesday or Thursday, that week is the 1st week of the next year. In case January 1 falls on Friday, Saturday or Sunday, the weeknumber is increased +1 with the previous weeknumber of last year. This is different from the "USA"-method, where the first week of the year depends on what day January 1 falls: in case it's a Sunday, PowerBI calculates week 1, otherwise it calculates a next weeknumber of the previous year for that week.


Outlook uses two settings to solve this:

- First day of week (in USA: Sunday, but in Europe, according to ISO weeknumbers: Monday)

- First week of year (in USA: Starts on January 1, but in Europe, according to ISO weeknumbers: First 4-day week).


In my opinion, the Timline slicer should be extended with the First Week Of Year setting to solve this issue of incorrect week numbers

Community Champion
Community Champion



Have you tried using Fiscal Year Start and Fiscal Day of Week?




Ignat Vilesov,

Software Engineer


Microsoft Power BI Custom Visuals

Frequent Visitor


Yes, I did. When you set Fiscal Year Start to 31st December you will get 1st week but year will be 2018 instead of 2019. The second problem is that next year will start on 30th December.

Thank you for your help.


Community Champion
Community Champion

Thanks for checking it.


We'll add such a feature into our backlog to implement it in upcoming sprints.


Ignat Vilesov,

Software Engineer


Microsoft Power BI Custom Visuals

Hi V-viig, 

I am facing the same issue and I was wondering if you have now implemented this new feature or not yet ? is there a workaround ?


thanks a lot for your help, AnneSo

Hi AnneSo,


my workaround was in "Format" - "Fiscal Year Start" to set Month to "January" and Day to "4".

But this willl only work for 2020/2021, of course!

In my case not a big problem as my users are only interested in last 12 weeks' data.

Hopefully the Custom Visual is being updated otherwise I have to again modify this setting until end of 2021!



Best regards




as I found out this workaround is not really the best solution as it shows wrong years, now (2021 instead of 2020 and 2022 instead of 2021):



So we really needed a patched version, please!


Best regards



Facing the same issue here (Europe weeks start on Monday / 2021 W1 should start on Jan 4th), tried the same workaround as akaefer, had the same results obviously ^_^


Forcing Fiscal Year to start at Jan 4th will work for 2021, but will mess up your data for other years, plus the display is buggy (showing year 2022 instead of 2021), even if the selected dates are indeed OK.


Interested in updates on a new version 🙂


Regards + Happy new year!


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