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What’s the Difference Between the Gregorian vs Julian Calendar?


Do you know the difference between the Gregorian vs Julian calendars? Do you know which one we use now? Read this guide to learn the differences and story.

Gregorian vs Julian calendar—what’s the difference?

The explanation will include some history and math, but no worries, we will try to make it as easy as possible!

The difference between the Julian and Gregorian calendars, their history, and usage in modern everyday life – we will go through all those points below.

calendar month names origins
Taken by E. Rothermel via unsplash.com. [Public Domain].

What’s the Difference Between the Gregorian and Julian Calendars?

The difference that is easiest to spot and to remember is that the Gregorian calendar is the one that we are using currently in the modern day around the world, and the Julian calendar was used in Europe and northern Africa before the Gregorian calendar was adopted in 1582. From 1582 and on, the whole world started to gradually switch to the Gregorian calendar.

Right now, the discrepancy between the Julian and Gregorian calendar equals 13 days, but by 2100 it will grow up to 14 days.

And now — let’s look closer at each of them.

Related Read: Here’s the Story Behind Each Month’s Names

Julian Calendar

The Julian calendar or Old Style calendar was established by Julius Caesar in 45 BC, and as you can see, that’s where its name comes from. It replaced the Roman calendar, which had only 355 days in a year. No wonder that by the time Caesar came to power, the Roman calendar was three months ahead of the solar year. 

That is why to fix the situation and put the things in order, Julius Caesar decided to change the whole dating system. His inspiration came from the Egyptian solar calendar, where they had 365 ¼ days, and he adopted it to his new calendar as well, making each fourth year a leap year.

The Julian calendar was almost identical to the Gregorian one which would be introduced centuries later. It had 12 months, with each month being either 30 or 31 days. Except, of course, February, which had 28 or 29 days depending if the year was leap or not. 

Wonder what could go wrong?

It was still inaccurate because of the formula that was used to calculate the leap years. Having a leap year each and every fourth year was too often and the solar year was miscalculated by 11 minutes. By the 16th century, it became too noticeable as the calendar started falling out of sync with the seasons.

Fun Fact: Even though there were 29 days in February (some of them), the month did not have February 29th, it simply had the date February 23rd twice!

Where is the Julian calendar used?

Nowadays, almost nowhere 🙂 Two exceptions are Eastern Orthodox churches which use it to establish the dates of their holidays, as well as the Berbers. 

Related Read: Why Does February Have 28 Days?

Gregorian Calendar

The Gregorian calendar, which can also sometimes be called the New Style calendar, was first introduced in 1582 by Pope Gregory XIII to save Easter. By this time, it was noticeable that the spring equinox and Easter needed to be realigned with the seasons. 

The structure of the calendar did not change much (as you know, we still happily have 12 months), but the calculations of the leap years were modified. Instead of assigning every fourth year 29 days in February, more sophisticated rules have been used (and have been in use ever since).

  • The year has to be evenly divisible by 4
  • The year that can be divided by 100 is not a leap year unless it can be also divided by 400. 

To switch to the Gregorian calendar, it was necessary to skip 10 days in 1582, however, for some countries, it took centuries to admit the necessity of the change. That is why, when the United Kingdom and its colonies decided to shift to the Gregorian calendar in 1752, they had to omit 11 days.

Slowly, because of growing globalization, the whole world had to go through the transition to the Gregorian calendar, no matter the calendar that was used before in the country.

Where is the Gregorian calendar used?

Everywhere around the world except North Korea. The Juche calendar has the same division of months and days in them but begins with the birth of Kim Il-sung, 1912. In 2011 it was only year 100 for inhabitants of North Korea. 

Mariia Kislitsyna
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Mariia Kislitsyna
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