8 Reasons Why the Gregorian Calendar Sucks (and How We Can Fix It)

Probably there is a calendar app on the device you're currently using to read this. Open it up and ask yourself the following question: Have you ever regarded the calendar you use every day as a perfect one? If your answer is "yes", I am here to tell you that you are wrong. In fact, the Gregorian calendar (that's what it's called) has a ton of imperfections and is certainly not the best calendar in the world.

I will only cover some basic points here because this is not the main topic. If you want to know more, you can do a Google search or look it up elsewhere.

The Gregorian calendar is a solar calendar introduced by Pope Gregory XIII in 1582. It is a minor modification of the Julian calendar, in that only the rules for determining leap years were tweaked. When it first came into use, 10 days were dropped to adjust for the discrepancy that the Julian calendar had accumulated over the centuries.

Now for the 8 reasons why the Gregorian calendar sucks.

Actually, this one is not exclusive to the Gregorian calendar - the Julian calendar also has irregular months. The month was originally a calendar element used to track the moon phases. This type of month was used as a calendar division in some of the earliest calendars developed by humans, including the ancient Roman calendar. When the Roman calendar was reformed into the Julian calendar, the original intercalary month was abolished and the month lengths tweaked to make the total number of days 365.

But why are the months irregular? There are two reasons to this:

- 1. The calendar is irrelevant to the moon phases, which means people are free to adjust month lengths however they want, as long as the year length is kept the same.

- 2. As a result, Julius and Augustus Caesar tweaked the lengths of the two months named after them (July and August) so that they are both 31 days long. This emphasized that the two emperors were equal and neither could be regarded as higher or lower. But where did the extra days come from? February, of course!

You are probably aware that the Julian calendar got replaced because it is too inaccurate. The calendar adds a leap day every four years without exceptions, which makes it fall behind the seasons by about three days every 400 years (1 day in 128 years, to be precise). The Gregorian calendar thus tries to adjust for this error by eliminating three leap days every 400 years. This is done by stipulating that a centenary year is a leap year only if it is divisible by 400.

The average year ended up to be 365.2425 days long - far more accurate than the Julian calendar, but still slightly longer than the tropical year of 365.24219 days. This causes the calendar to fall behind the seasons by 1 day every ~3200 years, but it may deviate even more within a 400-year leap cycle. We are going to talk about that in the next section.

While the new rules are still quite simple, they result in unevenly distributed leap days, which lead to seasonal errors in the calendar - a problem that is not present in the Julian calendar.

Take, for example, the period from March 1, 1900 to February 29, 2096. According to the rules of the Gregorian calendar, the year 2000 is a leap year. Thus, leap days are added every four years without exceptions during this period. This can cause the calendar to deviate from the seasons by more than one day, which is partially corrected by the upcoming elimination of the leap day in 2100.

Do you really need a leap cycle that's four centuries long to approximate the tropical year? The answer is: definitely not. You can do just as good - actually even better - with a cycle that's less than a quarter of 400 years in length: the 95-year leap cycle. A good approximation to the tropical year using this leap cycle is 365 ²³/₉₅ days = 365.2421053 days. A solar calendar employing this cycle will only drift ahead of the seasons by 1 day in ~10,000 years - three times as accurate as the Gregorian calendar. This approximation also has another advantage. The advantage? Read the next section to find out.

As you may know, the Earth's rotation is gradually slowing down (I covered this topic in a previous blog). The year length, however, does not change. For this reason, the discrepancy between the average Gregorian calendar year and the tropical year will grow at a steady rate. Over the long term, the calendar will fall behind the seasons at an increasing rate if this is not fixed. In contrast, the aforementioned 95-year leap cycle can actually pick up accuracy over time until the tropical year length drops below 365.2421053 days - because it's slightly lower than the current length of the tropical year.

On October 14, 1982, the very first 400-year leap cycle was completed, leaving us a discrepancy of around 3 hours. However, this accumulated error was not taken seriously by the general public, and people continued to use the Gregorian calendar. The current discrepancy of about 3 hours is not a huge one, but if people continue ignoring this error, which is accumulating slowly but surely, history will repeat itself and we will end up with an overwhelmingly inaccurate calendar once again. To make matters worse, it is much harder to succeed in a calendar reform now than in the past. We will explore this problem further in the next section.

Have you ever thought of doing a calendar reform? It might succeed if this was 400 years ago but right now it's just super difficult. Computers, mobile phones and many other electronic devices now have the Gregorian calendar incorporated into them, and the whole world relies heavily on the Gregorian calendar. If the calendar was to be reformed, all the electronic devices would have to be written new code that incorporates the new calendar, historical events would be harder to date, and ambiguity might arise from people's everyday conversations.

The Gregorian calendar is now used worldwide. Most recently, Saudi Arabia adopted the Gregorian calendar in 2016 to replace the Islamic calendar as the civil calendar of the country. The worldwide use of the calendar certainly has some advantages, but we are here to talk about its disadvantages. First of all, a calendar developed by a country or an ethnic group at any point in its history is a vital part of its culture. If those countries or ethnic groups were to stop using their own calendar and adopt the Gregorian calendar, an important element in their cultures would ultimately be lost. Secondly, just like how language diversity will be gone in a matter of a few centuries, calendar diversity will likely be gone before long if the whole world continues to use a single calendar.

The problems with the Gregorian calendar are very hard to solve, but it is not impossible. To fix its imperfections we can design a new calendar while keeping the basic elements of the Gregorian calendar unchanged. The following calendar proposal is for reference only.

- There are 12 months in a year, all of which bearing the same name as in the Gregorian calendar.

- Month lengths are as follows: 31 days in January, March, May, July, September and November; 30 days in April, June, August, October and December; 29 days in February for common years and 30 days for leap years.

- Leap years rules:

- 1. The calendar uses 95-year leap cycles; more complex rules are used as a tradeoff for short-term accuracy.

- 2. A year is a leap year if the year number modulus 95 is one of the following: 0, 4, 8, 12, 17, 21, 25, 29, 33, 37, 41, 45, 50, 54, 58, 62, 66, 70, 74, 78, 83, 87, 91.

- When the calendar is put into use, perform an initial calibration by determining the date of the previous vernal equinox and setting it as March 21.