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

Astronomical year numbering

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...

.

Conventions

• Within these tables, January 1 is always the first day of the year.
• The Gregorian calendar
  Gregorian calendar
  The Gregorian calendar, also known as the Western calendar, or Christian calendar, is the internationally accepted civil calendar. It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree signed on 24 February 1582, a papal bull known by its opening words Inter...
  
   did not exist before October 15, 1582. Gregorian dates before that are proleptic, that is, using the Gregorian rules to reckon backward from October 15, 1582.
• Augustus
  Augustus
  Augustus ;23 September 63 BC – 19 August AD 14) is considered the first emperor of the Roman Empire, which he ruled alone from 27 BC until his death in 14 AD.The dates of his rule are contemporary dates; Augustus lived under two calendars, the Roman Republican until 45 BC, and the Julian...
  
   corrected errors in the observance of leap years by omitting leap days until A.D. 8. Julian calendar
  Julian calendar
  The Julian calendar began in 45 BC as a reform of the Roman calendar by Julius Caesar. It was chosen after consultation with the astronomer Sosigenes of Alexandria and was probably designed to approximate the tropical year .The Julian calendar has a regular year of 365 days divided into 12 months...
  
   dates before A.D. 8 are proleptic, and do not necessarily match the dates actually observed in the Roman Empire
  Roman Empire
  The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....
  
  .

Conversion table

Year	Julian date	Gregorian date	Difference
−500	March 5	February 28
−500	March 6	March 1	−5
−300	March 3	February 27	−5
−300	March 4	February 28
−300	March 5	March 1	−4
−200	March 2	February 27	−4
−200	March 3	February 28
−200	March 4	March 1	−3
−100	March 1	February 27	−3
−100	March 2	February 28
−100	March 3	March 1	−2
100	February 29	February 27	−2
100	March 1	February 28
100	March 2	March 1	−1
200	February 28	February 27	−1
200	February 29	February 28
200	March 1	March 1	0
300	February 28	February 28	0
300	February 29	March 1
300	March 1	March 2	1
Year	Julian date	Gregorian date	Difference
500	February 28	March 1	1
500	February 29	March 2
500	March 1	March 3	2
600	February 28	March 2	2
600	February 29	March 3
600	March 1	March 4	3
700	February 28	March 3	3
700	February 29	March 4
700	March 1	March 5	4
900	February 28	March 4	4
900	February 29	March 5
900	March 1	March 6	5
Year	Julian date	Gregorian date	Difference
1000	February 28	March 5	5
1000	February 29	March 6
1000	March 1	March 7	6
1100	February 28	March 6	6
1100	February 29	March 7
1100	March 1	March 8	7
1300	February 28	March 7	7
1300	February 29	March 8
1300	March 1	March 9	8
1400	February 28	March 8	8
1400	February 29	March 9
1400	March 1	March 10	9
1500	February 28	March 9	9
1500	February 29	March 10
1500	March 1	March 11	10
Year	Julian date	Gregorian date	Difference
1582	October 4	October14	10
1582	October 5	October 15	10
1582	October 6	October 16	10
1700	February 18	February 28	10
1700	February 19	March 1	10
1700	February 28	March 10	10
1700	February 29	March 11
1700	March 1	March 12	11
1800	February 17	February 28	11
1800	February 18	March 1	11
1800	February 28	March 11	11
1800	February 29	March 12
1800	March 1	March 13	12
1900	February 16	February 28	12
1900	February 17	March 1	12
1900	February 28	March 12	12
1900	February 29	March 13
1900	March 1	March 14	13
2100	February 15	February 28	13
2100	February 16	March 1	13
2100	February 28	March 13	13

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

Absolute value

In mathematics, the absolute value |a| of a real number a is the numerical value of a without regard to its sign. So, for example, the absolute value of 3 is 3, and the absolute value of -3 is also 3...

, and subtracting a negative number is the same as adding the absolute value.

No guidance is provided about conversion of dates before March 5, -500, or after March 28, 2100 (both being Julian dates).

Years not evenly divisible by 100, or evenly divisible by 400

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. When adding, remember every year that this section applies to is a leap year in both calendars so February 29 must be included in the addition if applicable.

Years evenly divisible by 100 and not divisible by 400

Every year that fits into this section is a Julian leap year and a Gregorian common year. For unlisted dates, find the date in the table closest to, but earlier than, the date to be converted. Be sure to use the right column. If converting from Julian to Gregorian, add the number from the "Difference" column, but ignore February 29 if applicable. If converting Gregorian to Julian subtract but ignore February 29 if applicable.

External links

• Calendar Converter