Request: Multiple Calendars

I posted this request in the Q & A section but I think this topic would fit better in this portion of the forum as I would really love to see this feature in this app. I am not sure how to move topics or if I can do that.

I’ve been trying to use Aeon Timelines to track an overarching timeline that occurs in multiple worlds with different calendars but has a unifying calendar. My current workaround is to create Calendar Markers that repeat after the equivalent of a year has passed but this gets very cumbersome real fast as I have over 8 different calendars to keep track of.

For real-life applications, I am sure those who track events using the lunar calendar alongside the gregorian calendar would benefit greatly from being able to track with multiple calendars. There is also the 360-day calendar which is used in financial sectors.

It would be nice to be able to seamlessly convert between these calendars, have the calendars connect or begin from a certain date from another (useful for calendar transitions), and be able to switch between viewing the timeline from one calendar to another.


Seconding this request! My personal use-scenario is a bit niche, namely fiction set on both Mars and on Earth. However, even if calendars with days of different lengths wasn’t on the table, there are a number of calendars on Earth (Julian, Gregorian, Jewish, Chinese, etc.) that would be useful to switch between.


Yes please, I need this feature BADLY


Just piling on here for this feature…there were lots of positive responses to this when it was an Oct '21 Q&A topic. I still really need this to fully utilize AT3 (fictional setting with multiple overlapping calendars…though in my simple situation 1 day = 1 day in all calendars, no matter how labeled or counted). Fingers STILL crossed!


I won’t upgrade until this feature has been implemented. It’s crucial to how I want to work


I would also find this to be an extremely useful feature. Trying to outline a story occurring in parallel on two worlds – being able to have calendars for the events would be a godsend.

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Seeing that it’s unlikely this is going to be actioned any time in the future - does anyone have any tips on how to integrate this elsewhere, such as Excel? I currently have an Excel document that has dates etc on but it’s literally a list I wrote myself and took a long, long time lol.

I imagine adding this feature will also allow for calendar editing at any given moment, not only at the start of a project. Another feature that this app desperately needs.

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This would be extremely helpful especially for dual or more timeline stories.

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Just adding my voice to the chorus requesting this feature. Like several others here, I am working on a series of stories set across multiple worlds, where I have created a different calendrical system for each setting. At the moment I have created a rather convoluted MS Excel spreadsheet using Visual Basic functions to convert key story dates between these calendars, but it would be amazing to be able to set all of them up in Aeon Timeline instead.

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Exactly - I finally caved and bought the new version and managed to implement something similar to multiple calendars by using custom entities but it’s just not the same, and this only worked for me because in my fiction, the period where double calendars really matters is only a small amount of years, meaning less work for me when I set it up.

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I sorta want to see this and see if it will work for me too. I’ve been struggling to integrate multiple calendars. Mostly wondering if I should set up an excel sheet to convert it but it hasn’t been easy (and haven’t had the time)

Though I really wish we’d get word that whether this was being considered or not. I remember during the beta it was a very tentative maybe and something for post release

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Anyone have a sense of multiple calendars being implemented anytime soon? A definitive response from the developers on likelihood, priority, and feature specifics however simple, would be appreciated!


As soon as this feature comes available I will buy this product. Please make this happen thanks :pray:

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Any update on this? It would make things so much easier for complex stories. Thanks.

Let’s assume that multiple calendars are not high on the priority list of the Aeon developers. Then you can always get by with a tool.

Earlier in this thread, someone mentioned an Excel spreadsheet. I think this would be a good solution for those who are skilled enough with Excel to calculate an alternative date for each event and display it in its own column.

Another solution would be a script that reads the events either from the csv export or directly from the aeon file, and displays one or more alternative dates for each event in a table. Or write it all back into Aeon Timeline custom fields via CSV. Something like this can be done quite easily in all kinds of different programming languages.

The real tricky part for me is the specification for the alternative calendar systems. How can you specify how such calendars are related?
In its file, Aeon Timeline has a timestamp for each event that can be converted to a Gregorian date using the standard library routines of your programming language. Other custom calendar systems would all have to be derived from this timestamp, which is defined in seconds or something, from a fixed start date.

But I imagine that a user interface to set this up for other calendar systems could be complicated and confusing (that could also be the reason why it is not being picked up for Aeon). Wouldn’t it be? Does anyone have any concrete ideas?