Before we start
To convert a date to a Julian date format in Excel, you should understand basic functionality about formulae in excel like TEXT, YEAR, and DATE functions.
The Julian calendar is a widely recognized and historically significant calendar system. It was introduced by Julius Caesar in 45 BC as a way to standardize the length of the year and improve the accuracy of timekeeping. In this blog post, we will take a closer look at the Julian calendar, its history, and how it differs from other calendar systems.
The Julian calendar is a calendar system that was introduced by Julius Caesar in 45 BC. The calendar is based on the concept of a solar year, which is the time it takes for the Earth to complete one orbit around the sun. The Julian calendar has a year of 365.25 days, which is a slightly longer year than the Gregorian calendar, which has a year of 365.2425 days.
History of Julian Calendar
Before the introduction of the Julian calendar, the Roman calendar was used. This calendar was based on the cycles of the moon, which made it difficult to keep track of the seasons and agricultural cycles. As a result, Julius Caesar introduced the Julian calendar in 45 BC to better synchronize timekeeping and to bring stability to the Roman Empire.
The Julian calendar was widely adopted throughout the Roman Empire, and it became the standard calendar in Europe for more than 1,500 years. However, the Julian calendar was not perfect, and over time, it began to fall out of sync with the solar year. This led to the introduction of the Gregorian calendar in 1582, which is the calendar system that is used today in most countries around the world.
Difference from other calendar
The Julian calendar differs from other calendar systems in several ways. First, it has a longer year than the Gregorian calendar, which means that it is slightly less accurate when it comes to timekeeping. Second, the Julian calendar does not account for the leap year rule that was introduced in the Gregorian calendar. As a result, the Julian calendar falls out of sync with the solar year by approximately one day every 128 years.
Despite its flaws, the Julian calendar is still used in some parts of the world today. For example, the Orthodox Church uses the Julian calendar to calculate the dates of religious holidays such as Easter.
Excel Tutorial in Detail
“Julian date format” refers to a format where the year value of a date is combined with the “ordinal day for that year” (i.e. 14th day, 100th day, etc.) to form a date stamp.
There are several variations. A date in this format may include a 4-digit year (yyyy) or a two-digit year (yy) and the day number may or may not be padded with zeros to always use 3 digits. For example, for the date January 21, 2017, you might see:
1721 // YYD 201721 //YYYYD 2017021 // YYYYDDD
For a two-digit year + a day number without padding use:
For a two-digit year + a day number padded with zeros to 3 places:
For a four-digit year + a day number padded with zeros to 3 places:
This formula builds the final result in 2 parts, joined by concatenation with the ampersand (&) operator.
On the left of the ampersand, we generate the year value. To extract a 2-digit year, we can use the TEXT function, which can apply a number format inside a formula:
To extract a full year, use the YEAR function:
On the right side of the ampersand we need to figure out the day of year. We do this by subtracting the last day of the previous year from the date we are working with. Because dates are just serial numbers, this will give us the “nth” day of year.
To get the last day of year of the previous year, we use the DATE function. When you give DATE a year and month value, and a zero for day, you get the last day of the previous month. So:
gives us the last day of the previous year, which is December 31, 2015 in the example.
Now we need to pad the day value with zeros. Again, we can use the TEXT function:
Reverse Julian date
If you need to convert a Julian date back to a regular date, you can use a formula that parses Julian date and runs it through the date function with a month of 1 and day equal to the “nth” day. For example, this would create a date from a yyyyddd Julian date like 1999143.
=DATE(LEFT(A1,4),1,RIGHT(A1,3)) // for yyyyddd
If you just have a day number (e.g. 100, 153, etc.), you can hard-code the year and insert the day this:
Where A1 contains the day number. This works because the DATE function knows how to adjust for values that are out of range.
Online Free Resources
Thus, The Julian calendar is an important calendar system in the history of timekeeping. It was introduced by Julius Caesar in 45 BC as a way to standardize the length of the year and improve the accuracy of timekeeping.
While it has been largely replaced by the Gregorian calendar, the Julian calendar is still used in some parts of the world today. Understanding the Julian calendar can help us appreciate the development of timekeeping and how it has evolved over the centuries.
With this tutorial above, you can now use Microsoft Excel to convert your desired dates into Julian Format Easily. Also, templates and tools provided above can be a quick method to convert if you don’t want to learn the tutorial.