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How difficult would it be to make a simple Hebrew/Jewish Calendar covering the last 25 years using paper and pencils (including days of the week and corresponding Gregorian dates), with no access to the Internet, but knowing the current Hebrew and Gregorian date the day you began?

To make a simple, purely Gregorian calendar covering the last 25 years this way is a labourious task and takes about two or three evenings, but would be possible for any average person, provided they remembered when the last leap year was.

However, I came accross an article about Dr. Alan Rosen's The Holocaust's Jewish Calendars: Keeping Time Sacred, Making Time Holy, which discussed the illicit calendars made in Auschwitz. Obviously, these were made under unimagiably difficult conditions (AND they included the weekly Torah portions and holidays), but I was struck by the fact that the article mentioned one of the makers had studied under a teacher who "rigorously taught his young charges the rules for composing Jewish calendars". Furthermore, according to timeanddate.com, the Hebrew/Jewish Calendar features "a body of complex regulations, exceptions, and mathematical rules".

If you didn't include the holidays and Torah portions, how easy would it be for the average person to make such a calendar, and how long would it take?

Thank you.

  • To be clear, the average Jew definitely could not do this, unlike with the Gregorian calendar. Only people who have studied the subject specifically would be able to. – Double AA May 20 at 14:56
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If you have access to the internet for a little while, you can download my video where I go through the entire calculation. Video course on Jewish Calendar. There are software tools available there (calculator, web page for the Tur's keviyuyos) that are helpful as well.
You could do it with pencil and paper after watching that - I admit that I didn't! I'm guessing that it would take me a couple of hours to get the molad(s), because I'm not such a fast or accurate calculator, and then a few more to work out the Yomim Tovim, and [if I didn't have the Tur's chart] to figure out the parshiyos.
Now repeat 24 more times.
Update: I should add that if you do have the Tur's chart (OH 428) and the Arba'ah Sha'arim chart available on Wikipedia (https://en.wikipedia.org/wiki/Hebrew_calendar#Four_gates) or elsewhere, you could do this a lot faster. You basically just add a standard amount to the molad of the previous year, look it up in the Arba'ah Sha'arim chart to get the year type, then look in the Tur's chart for the whole calendar. Then repeat 24 times. Maybe an hour total once you'd get the hang of it?

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  • This is an incredibly helpful resource -- thank you so much. – AmethystMaria May 20 at 5:40
  • :) Please let me know any comments or suggestions you have.Thanks! – MichoelR May 20 at 11:03
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    I once was in a shul on Shabbos Mevarchim where they misplaced the Ezras Torah Luach (nobody else had one, and it's a small community so there were no other shuls to ask). I was going to get a Rambam Kiddush Hachodesh and try to figure out the molad myself. I was kind of disappointed when they found it. – Heshy May 20 at 11:22

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