13 Month Calendar

Hello welcome to our easy to use and easy to adopt 13 Month Calendar that we've named the...
'13 Ratio Calendar'

Here are the main features

• There are 13 months named A to M, this is to prevent confusion with other calendars.
• Each month has 28 days apart from the last month, month M. This has 29 days or 30 days on a leap year.
• The days of the week match the current Gregorian calendar.
• Easier to adopt than the International Fixed Calendar.

To view a working version (beta) of the calendar click here

An example of month H 2026

In the above example you can see that month H runs from 16 July to 12 August on the Gregorian calendar.

More to be added here soon. This is a work in progress.

2034 will be a special year.

It is not a new idea.

Humans have been watching the stars, seasons, moon and weather since we first had conscious thought. Looking for patterns. There have been thousands of different ways to measuring time, from following the moon to measuring the flow of water. And in all this time humans have created may calendars. Including 13 month calendars that almost perfectly track stages of the moon.

13 months just mathematically fit our year better. We all know it takes 365.25 days to lap our sun, we all also know this is what we call a year. Forget the 0.25 for now (we will come to this later) and lets do some maths.

365 divided by 12 is 30.417 and 365 divided by 13 is 28.077

But...

364 divided by 13 is exactly 28

So we have an extra day? No problem, that will be new years day 29 M.

It is inconsistent.

Fixed Days