Miscellaneous calendar converters

I like making silly calendar converters. It's fun! Here's a list of all the ones I've made and put online, ranked roughly from most to least useful:

• Islamic calendar
Perhaps the first useful calendar converter I have ever made. Note that this is the easier to predict tabular version, not the more traditional look-at-the-sky version, so dates may be off by a day or two.
• Hebrew calendar
Officially the second useful calendar converter I have ever made (thanks, Gauß!). As it happens, it's the first day of Passover 2024 when I write this so... yay, I guess.
• Chinese calendar
I owe the existence of this converter to the excellent book "Calendrical Calculations: The Ultimate Edition" by Edward M. Reingold and Nachum Dershowitz, and the just as excellent JavaScript library "calendrica-js" by Sarabveer Singh based on the aforementioned book.
• Bahá'í calendar
I owe the existence of this converter to the excellent book "Calendrical Calculations: The Ultimate Edition" by Edward M. Reingold and Nachum Dershowitz, and the just as excellent JavaScript library "calendrica-js" by Sarabveer Singh based on the aforementioned book.
• Mayan calendar
A classic, though not very interesting computation-wise.
• Babylonian calendar
A modern extrapolation. Years are counted from the reign of Nabonassar. Months are calculated via an Easter date algorithm (see below), and no attempt has been made to closely replicate any error and irregular intercalation known from historical records. Inspired by and made to loosely be in sync with @BabylonDate by Neil Freeman.
• Dozenal solstice calendar
A calendar I found via random internet scrolling, by Paul Rapoport. Meant to be used together with a base-12 number system, but not awful even without it. Years are counted from 9564 BC, supposely the most recent year in which the perihelion and Northern summer solstice fell on the same day, though that seems to be incorrect.
• Martian calendar
The Martian calendar that I use within the Big Timeline. Not the Darian calendar, but instead based on the Martian Business Calendar by Bruce Mills. Years are counted from 1955, as established in Clancy (2000) and subsequently adopted as consensus in the field. (Why don't more Martian calendars do this?!)
• 1982 Talossan calendar
A reskin of the Gregorian calendar, briefly adopted in the micronation of Talossa in 1982 and abandoned soon after since even the creator himself was confused by it.
• Tonal calendar
Another reskin of the Gregorian calendar, proposed by John W. Nystrom in 1862. The main gimmick is that it's base-16, or "tonal" as Nystrom called it. He also proposed his own hex digits that I have not bothered reproducing; this converter uses the conventional digits from 0 to F. Nystrom refered to the beginning of his calendar as "Christmas", even though it's... not. I don't know what's up with that.
• Enoch calendar
A calendar that consists of exactly 52 weeks – and thus drifts by 1.25 days per year. Supposedly revealed to the Biblical patriarch Enoch by the angel Uriel while they were travelling Heaven together. Years are counted from the year that Enoch entered Heaven alive, which I decided to equate with 2778 BC so that the calendar begins in spring and every year starts on a Wednesday as intended. Months are usually numbered, though I decided to name them after the Zodiac in Syriac instead. (It seemed thematically fitting, I don't know...)
• Intercalated Enoch calendar
Same as above, except that starting from year 4, every 7th year (every "sabbatical year", if you will) includes a special 7 days long mini-month, and every 4th sabbatical year (with two exceptions every 1820 years) that mini-month is twice as long. The upshot of this is that it makes the Enoch calendar actually, y'know, usable as a way to track the seasons. This intercalation method was proposed by John Pratt (2000). I decided to insert the mini-month between months number eight (‘Eqarbo, corresponding to Scorpio) and nine (Qešto, corresponding to Sagittarius) mainly because I thought it would be thematically fitting again; that way, it could correspond to Ophiuchus, and be named accordingly. I don't think anyone else would care about that, though...
• Easter calendar
Did you know that the Gregorian calendar has a (very janky) way of keeping track of the moon? This jank is used to determine when Easter Sunday is each year. You can also use it as a lunisolar calendar of its own right. I don't know why you would, but you definitely can. Changes made by me: Months are named after the Hebrew calendar, with "Nisan" refering to the month that Easter occurs in. Some tiny amounts of jank regarding missing or superfluous new moons around New Year have been removed based on Roegel (2014).
• Boryaworld calendars
A whole bunch of fictional calendars used for a group worldbuilding project. Hosted on a friend of mine's website.