Gregorian Holiday Calendars

Days of the Week

Like the regular calendar, Gregorian weeks also have seven days. However, instead of simple ordinal names, they are named after Norse and other deities, which makes them hard to remember. Here is a handy guide:

Months of the Year

Like the regular calendar in most years, the Gregorian year also has 12 months. Surprisingly, the Gregorian Rosh Chodesh does not correspond to a New Moon. As a result, the months tend to drift throughout the regular phases of the Moon, and it can be very difficult to tell when one month ends and a new month begins, let alone when holidays occur (note: Gregorian Rosh Chodesh is not recognized as a Christian holiday).

Not to be confused with the Gregorian days of the week, many of which are named for Norse deities, several Gregorian months are named after Roman deities, which persisted even after Vatican seceded from Rome in 5689.

Confusingly, some Gregorian months have Latin ordinal names, but they are not the correct ordinals. Tip: If you recognize the Latin prefix of an ordinally named month, simply add two to get the correct month number.

Months also vary in duration, ranging from 28 to 31 days, with no apparent pattern. Please refer to this table for assistance:

Pregnant Years

Like the regular calendar, the Gregorian calendar also has pregnant years to keep the holidays in line with the seasonsโ€”remember, even though it is not a lunisolar calendar, it is still a solar calendar.

Unlike the regular calendar, pregnant years do not add a thirteenth month. Instead, they add one day to the end of the second month, which is always the shortest month by several days, even during pregnant years. However, extending the month does not interfere with lunar cycles because the Gregorian calendar does not follow lunar cycles in ordinary years either.

The Gregorian calendar does not follow a straightforward 7-of-19-year cycle for pregnant years, and instead it has many complicated epicyclic rules to keep track of. However, a good rule of thumb is that there is usuallyโ€”but not alwaysโ€”a pregnant year every four years.

29 February is considered the second luckiest day of the year after Yom St. Patrick Haโ€™Kadosh, and Christians born on 29 February are considered very lucky.

Julian Calendar

The Julian calendar was the old version of the Gregorian calendar before Pope Gregory reformed it a bit and renamed it after himself. Most Christian people adopted Pope Gregoryโ€™s calendar during the first week of 5513, but Mizrahi Christians still consult the Julian calendar for some of their holidays.


The Gregorian calendar counts the years since the Christian prophetโ€™s bris, starting right away with year 1, and considered to have occurred in 3760. The Gregorian calendar does not use negative numbers for years; instead, they use โ€œBCโ€ to refer to years "before the circumcision." For example, Gregorian year 10 BC would have started during 3750 because there was no Gregorian year 0.

Chatzot lโ€™Chatzot

As we all know, there was evening and there was morning, a first day. And there was evening and there was morning, a second day. And so on. However, unlike ordinary days, Gregorian days do not begin at sundown. Instead, they begin several hours later, around chatzot layla (โ€œMidnightโ€ or 12:00 AM). Due to this complication, Christians need to know both which time zone they are in and have a clock set to the correct time to know when their holidays begin, unless of course they practice Tosefta.

Like regular days, Gregorian days are 24-hours long. If the time of day is not specified, GregCal will show both the day on which the Gregorian day begins at chatzot layla as well as the following day into which the Gregorian day extends. Tip: When a new day begins at sunset, it is still the same Gregorian day. During the night while you sleep, the Gregorian day changes, and it stays the same Gregorian day, past sundown, basically all the way through the time you fall asleep again the next night.ย 

You may consider that for followers of the Gregorian calendar, one day is considered to be the entire period that one is awake in between sleeping at night. Idiomatically, this means that in the middle of the night, even when it is a new Gregorian day, a follower of the Gregorian calendar will frequently refer to the previous Gregorian day as being the current day, until they sleep. Therefore, they may use terms like "today" when referring to events of the previous Gregorian day, because they have not slept yet.

Christian Holidays

Although it seems as if Christian holidays jump all over the calendar, with holidays falling โ€œearlyโ€ or โ€œlateโ€ in the year, you might be surprised to learn that many Christian holidays have fixed dates on the Gregorian calendar! They only seem to move around because the Gregorian calendar is merely a solar calendar and gets out of sync with the regular lunisolar calendar.

Note: Most Christian holidays span a single Gregorian day (24-hour period chatzot l'chatzot), even in the diaspora.

5784 (2023โ€“2024)

Christian American Heritage Month: Iyar

On 28 Iyar 5689 the Lateran Treaty took effect. Vatican became an independent Christian homeland. Today the US proudly recognizes our Christian-American siblings in the Christian diaspora thru the entire month of Iyar!

Date Converter

The Gregorian calendar is super complex. Thankfully, the wonderful programmers over at have figured out how to do this. Please visit their Date Converter and consider making a donation to those geniuses (no affiliation).

Satire. Inspired by (no affiliation) and JewWhoHasItAll (some affiliation).

ยฉ 2021โ€“2023 GregCal.