Gregorian calendar 
Gregorian calendar  2017 MMXVII 

2770 

1466 ԹՎ ՌՆԿԶ 

6767 

173–174 

1424 

2967 

65


2561 

1379 

7525–7526 

4713 or 4653 — to — 丁酉年 (Fire 4714 or 4654 

1733–1734 

3183 

2009–2010 

5777–5778 




2073–2074 


1938–1939 


5117–5118 

12017 

1017–1018 

1395–1396 

1438–1439 

(平成２９年) 

1950–1951 

106 

Gregorian minus 13 days 

4350 

民國106年 

549 

2560 

1483228800 – 1514764799 
The Gregorian calendar is internationally the most widely used
The calendar was a refinement to the
The Gregorian reform contained two parts: a reform of the Julian calendar as used prior to
The Gregorian reform modified the Julian calendar's scheme of leap years as follows:
Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the years 1600 and 2000 are.^{ [6]}
In addition to the change in the mean length of the calendar year from 365.25 days (365 days 6 hours) to 365.2425 days (365 days 5 hours 49 minutes 12 seconds), a reduction of 10 minutes 48 seconds per year, the Gregorian calendar reform also dealt with the accumulated difference between these lengths. The canonical Easter tables were devised at the end of the third century, when the vernal equinox fell either on 20 March or 21 March depending on the year's position in the leap year cycle. As the rule was that the full moon preceding Easter was not to precede the equinox, the date was fixed at 21 March for computational purposes and the earliest date for Easter was fixed at 22 March. The Gregorian calendar reproduced these conditions by removing ten days.^{ [7]}
To unambiguously specify the date,
The Gregorian calendar continued to use the previous
No.  Name  Length in days 

1 

31 
2 


3 

31 
4 

30 
5 

31 
6 

30 
7 

31 
8 

31 
9 

30 
10 

31 
11 

30 
12 

31 
The Gregorian calendar is a
Gregorian years are identified by consecutive year numbers.^{ [11]} The cycles repeat completely every 146,097 days, which equals 400 years.^{ [12]}^{ [13]} Of these 400 years, 303 are regular years of 365 days and 97 are leap years of 366 days. A mean calendar year is 365 days = 365.2425 days, or 365 days, 5 hours, 49 minutes and 12 seconds.^{ [14]}
A calendar date is fully specified by the year (numbered by some scheme beyond the scope of the calendar itself), the month (identified by name or number), and the day of the month (numbered sequentially starting at 1). Although the calendar year currently runs from 1 January to 31 December, at previous times year numbers were based on a different starting point within the calendar (see the "beginning of the year" section below).