Having a calendar that suits itself to easy generation of random dates by a die roll is something that I find very useful.

This idea dates back 20 years or so to my brother Robert’s campaign.

12 months with 28 days, for a year of 336 days. There are four seven day weeks in each month. It is easy and simple. Roll 1d12 for the month and 3d10-2 for the day of the month. Use it to determine the data a character was born. It is useful for determining when aging effects kick in and when to celebrate birthdays, if that is a custom in the game.

This simple system can determine any random date with a quick roll of 4 dice. One always knows what day of the 7 day week a given date falls. The months of the seasons fall with the first day of each season as the first day of the first month of that season. Spring is used as the first day of the year.

I even built an HTML page with the names of the months and days of the week Robert uses for his calendar. I printed one up all nice and fancy and give it to him, and he tells me that there is a festival between the last day of winter and the first day of spring. I pointed out to him that the method we had used for over 15 years never let anyone be born during the festival, or any random events happen then. He laughed and just let it slide.

I like the simplicity of twelve months of twenty-eight days. So what if years are shorter? It is a game.

To get a year closer to that of Earth, one can do 13 months of 28 days and get 364 days. One then needs to make a d13, or come up with a balanced way to roll for 13 possibilities. I’m sure someone is better at this and can just think of it and get the answer. If you do, let me know.

Another option that is close to the Earth year, is twelve 30 day months, for a year of 360 days. The months don’t line up , but the year comes out. For generating a day in a 30 day month use a d30 or a d6 to generate the tens to add to a d10. For example, 1-2 = add 0, 3-4 = add ten, 5-6 = add 20 to the number rolled on the d10.

If you have to have 365 days, then you need a way to roll or account for any festival days between months, or at the end of the year so that those days can have an event.

One can determine any random date in a year for incidents, war, battle, invasions, natural disasters, weather, etc. This can be used for the past as well as the current year or the future.

One thing I like from Oriental Adventures besides some of the weapons and spells are the yearly and monthly event tables. They give ideas for building one’s own tables.

Once you have such tables, you need to decide what date something happens. Then just determine what time of day something happens, if it is important for the exact time. I recommend staying with 24 hours days, unless you want to do a lot of table building, etc. You can roll a D6 for AM/PM and a d12 for the hour. Or roll a d6 and divide 24 by the result to get 4 hour increments, or a d8 for 3 hour increments, etc.

If you want to get down to the minute, roll a d12 to get within ten minutes and roll to determine if it is plus or minus 1 to 5 minutes from that point. Repeat for the exact second. This would be handy for a ritual that must begin or end at the right moment of an eclipse and determine when the hero have to act to stop the bad guy, assuming the bad guy is the one doing the ritual.

I found this article on making a grid like that of graph paper using Excel. I have not tried it with Libre Office or Open Office yet. I used it to build a blank calendar that I can name and number and note events and mark off days elapsed. I have 6 months in a column with room to the right of each month for some notes. If more room is needed, I could do 6 months on one side and 6 on the other.

If you use training to go up a level, players can fly through weeks and months, so planning out what happens in advance can make it interesting if they have to break training to deal with an emergency.

I’m old school in that computers were expensive when I was young and I’m used to paper. I work in the computer industry and find them very useful for gathering and storing data, but they become a hindrance to use during play. I do have a tablet with my PDFs of manuals I purchased through DriveThruRPG, if I need to find something fast and do a search. When I play online, I use it to hold my character sheet since I only have one viable monitor on my home computer.

I am sure that one could build a program or script to generate several millenniums of weather and events in a few minutes, but it takes a lot of the DM’s tweaking and tuning out of it. One does not need to generate every scrap of anything that could ever happen or has happened in the past.

What do you use for your calendar and random date generation?