How Often Does the Gregorian Calendar Repeat Itself?
If you live in the United States, then you've likely used the Gregorian calendar to track the passing of days, weeks, months and years. Each year contains 365 days (or 366 days during leap years), but not every year is precisely the same when it comes to the days of the week and dates matching up. That's why you may have celebrated your birthday on a Sunday last year and you’ll be blowing out your candles on a Tuesday this year.
But because the Gregorian calendar follows patterns and rules, there are times when the precise sequence of one year repeats in the future. This repetition also ensures that people can reuse calendars. So, before you toss out your old calendars, you might want to consider holding onto them for later use when the same dates and days align once more.
What Is the Gregorian Calendar?
Before delving into how often the Gregorian calendar repeats itself, it helps to define what this calendar is and how it came to be. Much of the world uses this calendar to specify and record time, specifically days and dates. Like many other calendars, the Gregorian calendar is based on the movements and positioning of the sun. For this reason, it's known as a solar calendar.
Each year is divided into 12 months, which are then divided into between 28 and 31 days. According to this calendar, we’re living in the 21st century, which is also known as the Second Millenium or the 2000s. However, the Gregorian calendar is not the only calendar, and it's certainly not the first.
Before the advent of this calendar type, much of Western civilization adhered to the Julian calendar. Before that, different groups used the Roman calendar and the Athenian calendar. Notably, nearly every prominent ancient civilization had its own calendar, and these various calendars didn't often adhere to the same rules.
One of the reasons why the Gregorian calendar has continued to find usage worldwide (despite its 1582 creation and implementation) is because it is a unifying, easy-to-understand concept and it generally keeps the months aligned with each year’s various seasons. However, some cultures and groups around the world don't recognize the Gregorian calendar or its structure. Instead, they continue to use the calendars their ancestors created. If you’re thinking about reusing a non-Gregorian calendar, it likely won’t be possible. While patterns are commonly found in other types of date-keeping systems, they don't repeat in the same manner or frequency as they do with the Gregorian calendar.
How Do Other Calendars Compare?
While 2012 brought quite a bit of attention to the Mayan calendar, there are several calendars that are still in use today. The Hebrew calendar and the Chinese calendar might be the most commonly recognized alternatives to the Gregorian model, and these options are thousands of years old. In contrast, our conventional method of date-keeping in the United States is only about 200 years older than the country itself.
The Gregorian calendar is far younger than many of the things we might consider relatively novel, and it's an update of the pre-existing Julian calendar — not a totally original concept. To make matters a little more complicated, it seems that the tradition of slightly altering a calendar type and then claiming it as a new thing has been going on for thousands of years.
Case in point? The Babylonian calendar consisted of 12 months and about 354 days, and it's not surprising that our current calendar is so similar to that ancient example. The types of calendars that are more notably different from the Gregorian model are those that didn’t emerge from Mesopotamia and its related cultures. Interestingly, the Chinese calendar repeats in much the same way as the Gregorian one — but it does so every 60 years instead.
How Often Does the Gregorian Calendar Repeat Itself?
The Gregorian calendar repeats itself in 28-year cycles. However, some patterns may repeat as few as every six years. Generally, leap years experience the lengthiest pauses between similar day-week patterns (28 years), while non-leap years may repeat every six or 11 years.
During this century, the pattern will hold to 11-11-6. This means that a calendar will repeat itself in 11 years. Eleven years after that, it will repeat again. Six years from that date, it will once again become applicable. An example helps to better illustrate this concept; take a look at the year 2001.
The first day of January 2001 was a Monday. Eleven years prior, in 1990, the first day of the new year had also been a Monday. The same was true of 1979. The next Monday-based New Year's Day after 2001 came in 2007. Thus, the cycle before 2001 had been 11-11, which left the six-year portion of the cycle and indicated that the next repetition would occur in 2007 (six years later).
Repeating Years to Keep Track Of
Now that you're more familiar with how often you can reuse calendars, it can help to take a quick look at upcoming years to determine when your calendar will work again. This way, you can begin to form a solid plan concerning which calendars you might want to use again and which you may want to recycle.
For example, if you've got a calendar that's appropriate for the year 2021, you might be pleased to know that you can use that same calendar again, completely accurately (save for the year, of course), in 2027, 2038, 2049 and even 2055. Let's explore some of the other repeating calendar years:
- A 2022 calendar can be reused in 2033, 2039, 2050 and 2061
- A 2023 calendar can be reused in 2034, 2045, 2051 and 2062
- A 2024 calendar can be reused in 2035, 2046, 2052 and 2063
- A 2025 calendar can be reused in 2036, 2047, 2053 and 2064
As you can see, reusing calendars you love or that are sentimental can be relatively easy. To effectively reuse your calendars, you'll need to resist filling in the boxes and margins with notes. Should you opt to write on your calendars, they could prove to be unique diaries of sorts that help you look back fondly on years past.