# Julian to gregorian calculator

## World's simplest time tool

With this browser-based application, you can convert any date from the ancient Julian calendar to the modern Gregorian calendar that we use today. You can paste several Julian dates into the input and calculate the corresponding Gregorian calendar dates in the output. If you enter several Julian dates (one per line), you can instantly see the difference in days between both calendars. Additionally, you can change the Gregorian calendar date format in the options. Created by computer nerds from team Browserling.

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Julian to gregorian calculator tool
What is a julian to gregorian calculator?

This is a quick online utility for calculating the Gregorian calendar date from the given Julian calendar date. The Julian calendar was introduced on January 1, 45 BC by Julius Caesar. In this calendar, the length of the year was 365¼ days, which means every four years the extra quarter of the day formed an additional day. A year with this extra day, by the way, is called a leap year. In 1582, the Julian calendar was replaced by the Gregorian calendar, which is the modern calendar that we use today. The Gregorian calendar is astronomically more accurate and the year lasts 365.2425 days. In the Gregorian calendar, years that are divisible by 4 are considered leap years, with the exception of years that are divisible by 100 and not divisible by 400. For example, the years 2100, 2200, 2300, and 2400 in the Gregorian calendar have 365, 365, 365, and 366 days (only the year 2400 is a leap year with an extra calendar day), however, in the Julian calendar, they have 366, 366, 366, and 366 days (there are 4 extra calendar days). It means that for every 400 years, the Gregorian calendar drifts ahead of the Julian calendar by 3 days. This is also the key reason why the Julian calendar was replaced by the Gregorian version. In this program, we implemented a precise mathematical algorithm that converts any date from one calendar standard to the other. Once you enter a Julian date in the format "YYYY-MM-DD" in the input, you'll get a Gregorian date in the output. Our tool can also convert multiple dates at once if you enter them in a column, one after another on separate lines. You can choose the Gregorian date format for the output by selecting a format from the list in the options or by creating a custom date format from a template using date component abbreviations (see the abbreviations cheat sheet in the options). You can also add or remove date padding (so that all date components are 2 or 4 digits long) and turn the time part into a 12-hour or 24-hour clock format. If you need to perform the reverse operation and convert a modern Gregorian date to the older Julian calendar, you can use our Gregorian to Julian Date Calculator utility. Timeabulous!

Julian to gregorian calculator examples
Click to use

Wikipedia Launch Date

This example takes a Julian calendar date 2001-01-02 as the input and converts it to a Gregorian calendar date. In the output, we get 2001-01-15 and it's an important date, as on this day, Wikipedia was created. As you can see, the difference between both calendar dates is 13 days. In fact, all dates from Feb 29, 1900 to Feb 28, 2100 of the Julian calendar (which correspond to the dates from Mar 13, 1900 to Mar 13, 2100 of the Gregorian calendar) have a difference of 13 days as compared to the Gregorian calendar.

2001-01-02

2001-01-15

**Required options**

Create a custom date format
using abbreviations. (Activated
by selecting custom mode).

Use zero-padded components
in the output Gregorian dates.

Use 12-hour time parts in the
output Gregorian dates.

Reform by Pope Gregory XIII

In this example, we go back in time when the transition from the Julian calendar to the Gregorian calendar was announced. The reform in the 16h century by Pope Gregory XIII shifted the calendar by 10 days. Namely, Thursday, October 4, 1582 (still in the Julian calendar) was followed by Friday, October 15, 1582 (now the Gregorian calendar) and October 5 to October 14 were skipped. In the output, we print the Gregorian date for the day that follows the final Julian calendar day in a custom format, and we also include the day of the week.

1582-10-05

Fri, October 15, 1582

**Required options**

Create a custom date format
using abbreviations. (Activated
by selecting custom mode).

Use zero-padded components
in the output Gregorian dates.

Use 12-hour time parts in the
output Gregorian dates.

Difference in Days Between Calendars

In the input of this example, we enter multiple Julian calendar dates that are all 400 years apart. We start the dates at "400-01-01 06:00:00" and end the list with the date "2400-01-01 00:00:00". The output shows that the difference in the number of days between both calendars grows as the years increase. To be precise, every 400 years the difference between the Julian and Gregorian calendars increases by 3 days. In the output, we remove the padding and display the clock time (which doesn't change between calendars) in a 12-hour format.

400-01-01 06:00:00
800-01-01 00:00:00
1200-01-01 18:00:00
1600-01-01 12:00:00
2000-01-01 06:00:00
2400-01-01 00:00:00

400-1-2 6:0:0 am
800-1-5 0:0:0 am
1200-1-8 6:0:0 pm
1600-1-11 12:0:0 pm
2000-1-14 6:0:0 am
2400-1-17 0:0:0 am

**Required options**

Create a custom date format
using abbreviations. (Activated
by selecting custom mode).

Use zero-padded components
in the output Gregorian dates.

Use 12-hour time parts in the
output Gregorian dates.

Pro tips
Master online time tools

You can pass input to this tool via

__?input__query argument and it will automatically compute output. Here's how to type it in your browser's address bar. Click to try!
https://onlinetimetools.com/convert-julian-date-to-gregorian-date

__?input__=2001-01-02&format=YYYY-MM-DD&custom-format=YYYY.MM.DD&padding=true&use-12-hour-clock=false
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