Conversion between Julian and Gregorian calendars

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The tables below list equivalent dates in the Julian and Gregorian calendars. Years are given in astronomical year numbering.

Contents

This is a visual example of the official date change from the Julian calendar to the Gregorian Julian to Gregorian Date Change.png
This is a visual example of the official date change from the Julian calendar to the Gregorian

Conventions

Conversion table

This table is taken from the book by the Nautical almanac offices of the United Kingdom and United States originally published in 1961. [2]

YearJulian dateGregorian dateDifference
−500March 5February 28
−500March 6March 1−5
−300March 3February 27−5
−300March 4February 28
−300March 5March 1−4
−200March 2February 27−4
−200March 3February 28
−200March 4March 1−3
−100March 1February 27−3
−100March 2February 28
−100March 3March 1−2
100February 29February 27−2
100March 1February 28
100March 2March 1−1
200February 28February 27−1
200February 29February 28
200March 1March 10
300February 28February 280
300February 29March 1
300March 1March 21
YearJulian dateGregorian dateDifference
500February 28March 11
500February 29March 2
500March 1March 32
600February 28March 22
600February 29March 3
600March 1March 43
700February 28March 33
700February 29March 4
700March 1March 54
900February 28March 44
900February 29March 5
900March 1March 65
YearJulian dateGregorian dateDifference
1000February 28March 55
1000February 29March 6
1000March 1March 76
1100February 28March 66
1100February 29March 7
1100March 1March 87
1300February 28March 77
1300February 29March 8
1300March 1March 98
1400February 28March 88
1400February 29March 9
1400March 1March 109
1500February 28March 99
1500February 29March 10
1500March 1March 1110
YearJulian dateGregorian dateDifference
1582October 4October 1410
1582October 5October 1510
1582October 6October 1610
1700February 18February 2810
1700February 19March 111
1700February 28March 1011
1700February 29March 1111
1700March 1March 1211
1800February 17February 2811
1800February 18March 112
1800February 28March 1112
1800February 29March 1212
1800March 1March 1312
1900February 16February 2812
1900February 17March 113
1900February 28March 1213
1900February 29March 1313
1900March 1March 1413
2100February 15February 2813
2100February 16March 114
2100February 28March 1314
2100February 29March 1414

Using the tables

Dates near leap days that are observed in the Julian calendar but not in the Gregorian are listed in the table. Dates near the adoption date in some countries are also listed. For dates not listed, see below.

The usual rules of algebraic addition and subtraction apply; adding a negative number is the same as subtracting the absolute value, and subtracting a negative number is the same as adding the absolute value.

If conversion takes you past a February 29 that exists only in the Julian calendar, then February 29 is counted in the difference. Years affected are those which divide by 100 without remainder but do not divide by 400 without remainder (e.g., 1900 and 2100 but not 2000).

No guidance is provided about conversion of dates before March 5, -500, or after February 29, 2100 (both being Julian dates).

For unlisted dates, find the date in the table closest to, but earlier than, the date to be converted. Be sure to use the correct column. If converting from Julian to Gregorian, add the number from the "Difference" column. If converting from Gregorian to Julian, subtract.

See also

Related Research Articles

Astronomical year numbering is based on AD/CE year numbering, but follows normal decimal integer numbering more strictly. Thus, it has a year 0; the years before that are designated with negative numbers and the years after that are designated with positive numbers. Astronomers use the Julian calendar for years before 1582, including the year 0, and the Gregorian calendar for years after 1582, as exemplified by Jacques Cassini (1740), Simon Newcomb (1898) and Fred Espenak (2007).

The Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year. The Julian calendar is still used as a religious calendar in parts of the Eastern Orthodox Church and in parts of Oriental Orthodoxy as well as by the Amazigh people.

A leap year is a calendar year that contains an additional day compared to a common year. The 366th day is added to keep the calendar year synchronized with the astronomical year or seasonal year. Because astronomical events and seasons do not repeat in a whole number of days, calendars that have a constant number of days in each year will unavoidably drift over time with respect to the event that the year is supposed to track, such as seasons. By inserting ("intercalating") an additional day, a leap day, or month, a leap month, into some years, the drift between a civilization's dating system and the physical properties of the Solar System can be corrected.

<span class="mw-page-title-main">Lunisolar calendar</span> Calendar with lunar month, solar year

A lunisolar calendar is a calendar in many cultures, combining lunar calendars and solar calendars. The date of Lunisolar calendars therefore indicates both the Moon phase and the time of the solar year, that is the position of the Sun in the Earth's sky. If the sidereal year is used instead of the solar year, then the calendar will predict the constellation near which the full moon may occur. As with all calendars which divide the year into months there is an additional requirement that the year have a whole number of months. In some case ordinary years consist of twelve months but every second or third year is an embolismic year, which adds a thirteenth intercalary, embolismic, or leap month.

<span class="mw-page-title-main">Year</span> Time of one planets orbit around a star

A year is the time taken for astronomical objects to complete one orbit. For example, a year on Earth is the time taken for Earth to revolve around the Sun. Generally, a year is taken to mean a calendar year, but the word is also used for periods loosely associated with the calendar or astronomical year, such as the seasonal year, the fiscal year, the academic year, etc. The term can also be used in reference to any long period or cycle, such as the Great Year.

The proleptic Julian calendar is produced by extending the Julian calendar backwards to dates preceding AD 8 when the quadrennial leap year stabilized. The leap years that were actually observed between the implementation of the Julian calendar in 45 BC and AD 8 were erratic.

The Julian day is the continuous count of days since the beginning of the Julian period, and is used primarily by astronomers, and in software for easily calculating elapsed days between two events.

<span class="mw-page-title-main">Nisan</span> 1st month of the Hebrew calendar

Nisan in the Babylonian and Hebrew calendars is the month of the barley ripening and first month of spring. The name of the month is an Akkadian language borrowing, although it ultimately originates in Sumerian nisag "first fruits". In the Hebrew calendar it is the first month of the ecclesiastical year, called the "first of the months of the year", "first month", and the month of Aviv בְּחֹ֖דֶשׁ הָאָבִֽיב ḥōḏeš hā-’āḇîḇ). It is called Nisan in the Book of Esther. It is a month of 30 days. In the year 2024, 1 Nisan will occur on 9 April. Counting from 1 Tishrei, the civil new year, it would be the seventh month, but in contemporary Jewish culture, both months are viewed as the first and seventh simultaneously, and are referred to as one or the other depending on the specific religious aspects being discussed.

<span class="mw-page-title-main">Date of Easter</span> Calculation of its date

As a moveable feast, the date of Easter is determined in each year through a calculation known as computus. Easter is celebrated on the first Sunday after the Paschal full moon, which is the first full moon on or after 21 March. Determining this date in advance requires a correlation between the lunar months and the solar year, while also accounting for the month, date, and weekday of the Julian or Gregorian calendar. The complexity of the algorithm arises because of the desire to associate the date of Easter with the date of the Jewish feast of Passover which, Christians believe, is when Jesus was crucified.

The epact used to be described by medieval computists as the age of a phase of the Moon in days on 22 March; in the newer Gregorian calendar, however, the epact is reckoned as the age of the ecclesiastical moon on 1 January. Its principal use is in determining the date of Easter by computistical methods. It varies from year to year, because of the difference between the solar year of 365–366 days and the lunar year of 354–355 days.

Dominical letters or Sunday letters are a method used to determine the day of the week for particular dates. When using this method, each year is assigned a letter depending on which day of the week the year starts. The Dominical letter for the current year 2024 is GF.

A calendar era is the period of time elapsed since one epoch of a calendar and, if it exists, before the next one. For example, it is the year 2024 as per the Gregorian calendar, which numbers its years in the Western Christian era.

The determination of the day of the week for any date may be performed with a variety of algorithms. In addition, perpetual calendars require no calculation by the user, and are essentially lookup tables. A typical application is to calculate the day of the week on which someone was born or a specific event occurred.

The Tabular Islamic calendar is a rule-based variation of the Islamic calendar. It has the same numbering of years and months, but the months are determined by arithmetical rules rather than by observation or astronomical calculations. It was developed by early Muslim astronomers of the second hijra century to provide a predictable time base for calculating the positions of the moon, sun, and planets. It is now used by historians to convert an Islamic date into a Western calendar when no other information is available. Its calendar era is the Hijri year. An example is the Fatimid or Misri calendar.

<span class="mw-page-title-main">Doomsday rule</span> Way of calculating the day of the week of a given date

The Doomsday rule, Doomsday algorithm or Doomsday method is an algorithm of determination of the day of the week for a given date. It provides a perpetual calendar because the Gregorian calendar moves in cycles of 400 years. The algorithm for mental calculation was devised by John Conway in 1973, drawing inspiration from Lewis Carroll's perpetual calendar algorithm. It takes advantage of each year having a certain day of the week upon which certain easy-to-remember dates, called the doomsdays, fall; for example, the last day of February, 4/4, 6/6, 8/8, 10/10, and 12/12 all occur on the same day of the week in any year.

In astronomy, a Julian year is a unit of measurement of time defined as exactly 365.25 days of 86400 SI seconds each. The length of the Julian year is the average length of the year in the Julian calendar that was used in Western societies until the adoption of the Gregorian Calendar, and from which the unit is named. Nevertheless, because astronomical Julian years are measuring duration rather than designating dates, this Julian year does not correspond to years in the Julian calendar or any other calendar. Nor does it correspond to the many other ways of defining a year.

A year zero does not exist in the Anno Domini (AD) calendar year system commonly used to number years in the Gregorian calendar ; in this system, the year 1 BC is followed directly by year AD 1. However, there is a year zero in both the astronomical year numbering system, and the ISO 8601:2004 system, the interchange standard for all calendar numbering systems. There is also a year zero in most Buddhist and Hindu calendars.

<span class="mw-page-title-main">Mesoamerican Long Count calendar</span> Calendar used by several pre-Columbian Mesoamerican cultures

The Mesoamerican Long Count calendar is a non-repeating base-20 and base-18 calendar used by several pre-Columbian Mesoamerican cultures, most notably the Maya. For this reason, it is often known as the MayaLong Count calendar. Using a modified vigesimal tally, the Long Count calendar identifies a day by counting the number of days passed since a mythical creation date that corresponds to August 11, 3114 BCE in the proleptic Gregorian calendar. The Long Count calendar was widely used on monuments.

The Gregorian calendar is the calendar used in most parts of the world. It went into effect in October 1582 following the papal bull Inter gravissimas issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years differently so as to make the average calendar year 365.2425 days long, more closely approximating the 365.2422-day 'tropical' or 'solar' year that is determined by the Earth's revolution around the Sun.

The proleptic Gregorian calendar is produced by extending the Gregorian calendar backward to the dates preceding its official introduction in 1582. In nations that adopted the Gregorian calendar after its official and first introduction, dates occurring in the interim period of 15 October 1582 to the date on which the pertinent nation adopted the Gregorian calendar and abandoned the Julian calendar are sometimes 'Gregorianized' also. For example, the birthday of U.S. President George Washington was originally dated 11 February 1731 because Great Britain, of which he was born a subject, used the Julian calendar and dated the beginning of English years as 25 March. After Great Britain switched to the Gregorian calendar, Washington's birthday was dated 22 February 1732 proleptically, according to the Gregorian calendar applied backward. This remains the modern dating of his birthday.

References

  1. ↑ Explanatory_Supplement 1961, pp. 410–11.
  2. ↑ Explanatory_Supplement 1961, pp. 416–18.
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