গ্রেগরিয়ান পাঞ্জী (ইংরেজী: Gregorian calendar বুলতারা পাঞ্জী এহান পৃথিবীর হাব্বি দেশে চলের বুললেউ য়্যাকরের। এহান জুলিয়ান পাঞ্জীত্ত পতিয়া হঙকরিসিহান যেহান পয়লাকা কালাব্রিয়ান ডক্টর আলইয়াস লিলিয়াসে প্রস্তাব করিয়া বারো চালেইলতা পোপ গ্রেগরি ত্রয়োদশে যেগর নাংহান ইলয়া এহানর নাংহান থনা ইল।
The Gregorian Calendar was devised both because the mean year in the Julian Calendar was slightly too long, causing the vernal equinox to slowly drift backwards in the calendar year, and because the lunar calendar used to compute the date of Easter had grown conspicuously in error as well.
The Gregorian calendar system dealt with these problems by dropping a certain number of days to bring the calendar back into synchronization with the seasons, and then slightly shortening the average number of days in a calendar year, by omitting three Julian leap-days every 400 years.
The Gregorian solar calendar is an arithmetical calendar. It counts days as the basic unit of time, grouping them into years of 365 or 366 days. The solar calendar repeats completely every 146,097 days, which fill 400 years, and which also happens to be 20871 seven-day weeks. Of these 400 years, 303 (the "common years") have 365 days, and 97 - the leap years - have 366 days. This gives an average year length of exactly 365.2425 days - or 365 days, 5 hours, 49 minutes and 12 seconds.
A Gregorian year is divided into twelve months of irregular length (but note that there is a period of 153 days divided over 5 months in an alternating pattern from March to July that repeats from August to December):
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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).
Leap years are all years divisible by 4, with the exception of those divisible by 100, but not by 400. These 366-day years add a 29th day to February, which normally has 28 days. Thus, the essential ongoing differential feature of the Gregorian calendar, as opposed to the Julian calendar, is that the Gregorian omits 3 leap days every 400 years. This difference would have been more noticeable in modern memory, were it not for the fact that the year 2000 was a leap year in both the Julian and Gregorian calendar systems.
The intercalary day in a leap year is known as a leap day. Since Roman times 24 February ( bissextile) was counted as the leap day, but nowadays 29 February is regarded as the leap day in most countries.
Although the calendar year runs from 1 January to 31 December, sometimes year numbers were based on a different starting point within the calendar. Confusingly, the term "Anno Domini" is not specific on this point, and actually refers to a family of year numbering systems with different starting points for the years. See the section below for more discussion of this issue.