I’ve been into using Week Numbers for the last few years. So much of teaching happens at the unit of ‘week.’1 Part of that has been the benefits of having a week note in Obsidian. I also have week numbers turned on in Fantastical and other places to quickly refer to.
As I was laying out some things for the start of 2027, I noticed that Obsidian’s week numbers and Fantastical’s didn’t agree. Fantastical had a Week 53 to close out 2026, but Obsidian started with a Week 1 during the same week (the week from December 27–January 2). I initially assumed Obsidian was wrong and spent some time fighting with that plug-in, before realizing Apple Calendar agreed with Obsidian, rather than Fantastical.
So after a bit of digging, I realized Fantastical was using the ISO standard, rather than the US…erm, standard?2 So I reached out to Flexibits’ great support team for an answer. They got back to me quickly to run a URL scheme to fix this, which was
x-fantastical3://defaults?key=UseNonISOWeekNumbers&value=1&type=bool&group=1
Hidden preferences are alright, though I wish they had some documented. Doing some searching, I found that MacSparky had posted some a few years back if that helps anyone else.
- The last time I had a lesson schedule, I was blessed enough to have it on a weekly cycle, rather than a day-based cycle. And several years where my bands that didn’t meet daily were also based on the day of the week, rather than another type of cycle. ↩
- Quoting Wikipedia: “In years where 1 January is a Friday, ISO-8601 will be different, but the rest will agree.” I am a diehard guy for Sunday being the first day of the week, but I don’t really care past that how the first week of the year is reconciled. I just want things to work consistently and in a way that assists my communication with others. ↩
