Sometimes I wish I had a direct line to the GCal team.

Okay. I have received some feedback on the experiment I have been running (see post below this one).

From what I could determine, there are two negative side effects from changing the length of the week number events. 1) All days are marked as busy (all days are bold in the mini-calendar). Previously only the first day in the week was marked as busy. 2) The week numbers appear on every day in the Agenda view.
Despite of this, I have decided that the benefits outweigh the side effects, and I will apply this change to all week numbers in the coming days.

For those of you who despise this change, there is a remedy! You can simply switch to Google's own week number calendar (instructions above). Their calendar is exactly the same as my calendar was before, with the exception of a different icon.

My final thoughts on this is that I don't think Google has successfully added week numbers to Google Calendar. I think week numbers need to be integrated in the same manner as normal date numbers. Any "solution" that requires an extra calendar will be flawed in some way. My hopes that Google will make week numbers a first class citizen is unfortunately very low.

I am currently running an experiment that should make it more convenient to view the week numbers on mobile phones like Android. I have modified to length of the events so that they span the whole week. This should make the icon appear on every day when using the day view. The calendar will look exactly the same on the web, so you should not notice any difference there. The only difference I have noticed is that the week number icon appears on every day when you are using the day view there too, but that is expected and also pretty nice.

I have only applied this for week 37, 38 and 39 and only on the Mondays calendar. If this experiment works out then I will proceed with updating all future week numbers.

I got this tips from a user like yourself and that is how this update started. Note that I do not own an Android device myself and therefore your feedback is important! Report any problem to me!

I have added week numbers for 2014 and 2015. I have also updated the gadget to make it more useful. For my Swedish users, I recommend you to check out my name days calendar, which I have also recently updated.

Tip: You can also use the gadget in Gmail by adding this address with Gmail Labs: http://sites.google.com/site/gcalweeknumbers/Home/calendar-gadget.xml

The calendar seems to be working again. There have been no response from Google but I guess there was just some database issues on their end. Anyway, I'm just glad I didn't have to create a whole new calendar. :)
On another note, I have launched a new calendar which adds Swedish name days to your calendar. If this becomes popular I might start name days calendars for other countries. Consider it to be in Beta status for now.

Hi everyone. It seems like a new problem has come up. Currently I am getting the message "The following are not Google Calendar users: g0k1sv1gsdief8q28kvek83ps4@group.calendar.google.com" when I load Google Calendar. This is not my fault, and most likely a problem on Google's end. I have written a post in their help group, so hopefully someone from Google will fix it. You can help by posting in the thread demanding support :). In the mean while, you can try out Google's own week numbers. More information on how to add them can be found above on this page.

Hi everyone. I have gotten some reports that my week number calendar is taking a lot of time to load. I have not changed anything, so it is probably Google's fault :D. I have made a thread on Google's help center, but it might take a while to go through the official channels. In the mean time, you can add Google's own week numbers (explained above), which should be more stable (though uglier :). I have also made some changes to this site so Google's official week numbers is more noticeable. I will make another post when the performance problems have been resolved.

Note that I can not help you customize the week numbers. I have received so many requests and I do not have time to help everyone! All the help you need is on this page and in the documentation that Google provides. Please do not email me about this.

I have just updated the icons to a new set of icons submitted by Marco Baumgarten. These new icons look a lot better on backgrounds other than white, like when using the Firefox addon Google Redesigned. We are planning to release a new calendar with a new set of icons as well. Send any feedback to me.
I have also noticed that it is now very easy to add Google's week numbers. Read the section above.

I have just made a gadget for Google Calendar. Read the section above for more info.