World-building and calendars

If I'm going to track the time of a given chapter, there are two things I have to keep track of: date and time. Ignoring time for now, tracking dates in a fictional world is somewhat difficult.

Assuming that the fictional world doesn't use ISO dates (yyyy-mm-dd), which none of mine do, then I have to figure out the calendars on my own (and eventually write programs to coordinate them between the different cultures/calendars). There are also little issues of how you display them in a story (or in personal notes).

This is part two of a four part series:

  • Part 1: My reasons for doing this
  • Part 2: Some theory on what makes an interesting fictional calendar
  • Part 3: An example of creating a messy calendar
  • Part 4: Creating a visual representation of the calendar

Fictional Calendars

There are a lot of components to world-building. Calendars are one part of the bigger picture. It is also a part that I feel is frequently glossed over and moved beyond by many creators.

Time keeping can be the source of plots and stories. Not every world has a Halloween or they may have more than one. I love Kingdom of Loathing as they introduced different holidays over the years, it adds depth and fun to the game.

When you have calendars that people believe in, you have things like the Y2K scare, the panic in 1899, the whole end of the Aztec calendar, or even the terror that will strike in February 2038 when the Unix timestamp would hypothetically roll over. All great things to hang plots on.x

Different calendars are a wonderful source of stories. More so when they are close, but slightly different. If you have a two thousand year old machine that, at the stroke of midnight will destroy the world, which calendar do you use? Which midnight? What if they use Julian days which roll over at noon?

Hollywood seems to think that all ancient civilization planned ahead so their date would match the Gregorian Calendar instead of whatever was used when said plans started. More specifically, the Gregorian calendar started in 1582. That isn't that long ago and it did change leap year calculations.

The movie End of Days is a good example of using modern time tracking for the plot. The conception must happen at the stroke of the millennium and it was planned for thousands of years. They should be off by a few days, that would make an interesting twist if everyone goes to stop the coming of the ultimate evil, only to find out that the real conception is going to happen six days later. You know, when everyone has relaxed and thought they saved the world.

Neat Calendars

Most fictional worlds I've seen have "neat" calendars. Twelve month of twenty-nine days. Eleven months of forty days. It is the starting point of a lot of calendars, including our own. I'm guilty of the same thing since I really like thousand-day years because it formats nicely to 000-999.

They also have names that follow a pattern. It could be "something-month, something-month" or long, flowery names that are utterly impractical for day-to-day use. If you look at the Gregorian calendar, it has short names (May, June) and long ones (September, February).

When I see a neat calendar, I feel there is a lost opportunity to show progression and depth in a world. Creators seem to assume that somehow the world was perfectly in tune with the calendar's cycle and that someone was precise enough to figure out the exact length of day on the first try. Pretty good for cultures that have been around for thousands of years but still haven't invented the toilet.

That said, a purely random calendar looks almost as bad as a neat one. If the month lengths are 7, 45, 19, and 35, you have an impractical system. The Gregorian Calendar only differs by 4 days for any given month (28 to 31 days). This is more practical because it is easier to remember than "seven days come January, forty-five in February, then 19, 35, 83, 2, 41, 36...".

Starting Neatly

Calendars start neat, then reality happens. It appears that our own world is simply twelve months of thirty days. Yeah, it's off by five and some, but you could easily start with that point.

I like calendars should start with that idealistic neatness. It just seems that most world builders stop at that point. It's "good" enough to figure out the fun things like the entire rest of the world.

But, I don't think it takes much to mess it up a bit, put in some interesting hooks, and still get a usable, messy calendar to inflict the world with. Even better yet is having competing calendars splitting apart and merging again later as the world advances.


The tools to measure time are constantly improving. When you only have ticks on the side of a tree, you probably can't get the number of seconds in a year precisely. When you have an atomic clock, it's a lot easier. That is why we had calendars that make a few smaller and smaller changes to the previous one (Gregorian previous and our current leap minutes).

The broadest strokes of a calendar change is that refinement. The better the tools, the more the world has to put in "patches" to get it to work. Add a day every four, remove it every hundred.

This is also why Fedran's solar cycle is 368.3087 days long. Why? Because I want to have the gradual improvement over the centuries.


Politics are the other big reason for changing a calendar: an emperor might want to have a month named after him, an invading country forces their own world view, or trade requires a change to make it profitable. I consider religion to be one of these. These changes can result in messy calendars that aren't any more accurate the previous one, but has little bits shuffled here and there.

The easiest changes I've seen politics inflict on a calendar are changing the names of months or stealing a day from another one cycle to another. It's the minor shuffle that, take time after time, messes up the calendar.

Mixing it up

These can be combined together. When I create a calendar, I try to create 5-8 significant points in the evolution of the calendar. During those times, there is a bit of refinement and politics that alter it. And the resulting changes are, I think, a bit more realistic and create a richer world.


Doing this is work. For someone who is just trying to get enough there to have an exotic sounding month for their novel, it may be overkill. If someone really just wants to focus on other aspects, a simple calendar might be enough.

For me, I think I'm going to be in this world for a while. I want to have a comfortable foundation to track my stories but also to maybe give it richness in later tales.

It's also a fun diversion for a couple of days.