How to Calculate the Molad in Your Head for the Next Century and More

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By Rabbi Yair Hoffman for 5tjt.com

You are in the mountains for Shabbos. You are davening in a place where there is no new calendar or newspaper telling you the time of the next Molad – and it is Shabbos mevorchim.  Many of us had had this happen -especially when there is no Gabbai.

What do you do?

The Molad or “new lunation” is the calculation of when the new moon, on average, will appear in Jerusalem, Israel.  At that exact moment, on average, it begins when the moon comes between the earth and the sun.  Traditionally, the exact time is announced in shul between Shacharis and Mussaf before Rosh Chodesh Bentching. Here is a method of calculating the Molad by heart for the next century or more. Essentially, it involves memorizing two statements as well as a concept. We will begin with the two statements that must be memorized and then we will describe the concept.

Yes, the following two statements are bizarre, but they will help in the calculation. The idea of being able to calculate the Molad in any given month has been described as the “wisdom and understanding of the Jewish nation in the eyes of the gentiles.” It is a good thing to know.

FIRST STATEMENT

Back in Taives of ’82, I Sat with a 13 year old and learned the 39 malachos till he turned 14.

That’s the first statement that needs to be memorized. So let’s just repeat it aloud again. Back in Taives of ’82, I Sat with a 13 year old and learned the 39 malachos till he turned 14.

Now let’s discuss its meaning. It essentially is a means of memorizing when the molad was this past Taives of 5782. Taives of 5782 will act as our point of origin or reference, when calculating all future Molads. It occurred on SATURDAY at 13:39 PM (1:39 PM) and 14 Chalakim. One Chailek is 1/18th of a minute (3 and 1/3 seconds). A good way to remember the 39 minutes is that it is the same as the 39 malachos.

* There is a Yesoma who, boruch Hashem, just got engaged.  If anyone would like to assist in making her chasuna please donate here or contact the author.*

THE SECOND STATEMENT

Now the second statement that needs to be memorized:

Every month since then, every day and a ½, for 44 minutes I add one.

Since that is the second statement that needs to be memorized, let’s repeat it aloud again. Every month since then, every day and a half, for 44 minutes I ‘add one.

Now let’s discuss the meaning of this second statement. In order to calculate the day and time of any future Molad past that of Taives 5782, we add 1 day and twelve hours and 44 minutes and one more chailek for every additional month.

SIMPLE EXAMPLE

For example, if we just wish to calculate the molad for one month afterward, we add a day and a half to Saturday afternoon at 13:39 PM (1:39 PM) and 14 Chalakim.  So we get Monday Morning at 1:39 AM.  Then we add the 44 minutes, and we get Monday morning at 2:23 AM.  Now we just add one more chailek to the fourteen, and we get the Molad for Shvat  – Monday Morning at 2:23 AM and 15 chalakim.

MORE COMPLEX EXAMPLE

Now let’s say we wish to calculate the Molad for Taives of 5783 – next year, a full thirteen months forward (because 5782 is a leap year where we add an extra month of Adar.) So we multiply 1 and ½ by 13 and we get 19 and a half. Since we don’t care about the weeks here, we subtract from this number any multiple of 7. So we are left with 5 and one half. We add 5 and a half days to Saturday afternoon and we get Friday morning at 1:39 AM. Now we multiply 44 by 13 (which is 10 plus 3) and we get 440 plus 3 times 44 which is 120 plus 12 or 132. So the total minutes we add are 572 – which is 540 plus 32. Thus, we add nine hours and 32 minutes to 1:39 AM and we get 11:11 AM.  Now the last thing we do is add 13 Chalakim to the 14 Chalakim of Teves of 5782 (27 Chalakim = 1 minute + 9 Chalakim) and we get Friday Morning, 11:12 AM and 9 Chalakim.

THE CONCEPT

But how do we know when exactly we add an extra month? When we are calculating the Molad for, say, ten years hence, how can we take into account the extra leap months?

For this, it is best that we understand the following concept. Although in the non-Jewish secular calendar we generally have a leap year every four years, this is not the case in the Jewish calendar. The Jewish calendar has a 19 year cycle in which there are seven leap years.

We can call this calendar the Guach Luach, because the seven years are years 3, 6, 8, 11, 14, 17, and 19. [Three, six and eight are represented by the gimel vov and ches in Hebrew]. Each of those years in the 19 year cycle are leap years where an entire extra month of Adar is added. We do this to fulfill the Mitzvah of always celebrating Pesach in the spring (Shamor es chodesh HaAviv.)

The year 5776 was the 304th completion of the 19 year cycle. This year, 5782, is the 6th year of the 19 year cycle. of the 305th cycle. It is a leap year. You must keep the extra months in mind when calculating a future Molad that will take you into these leap years. What you can do is simply subtract 76 from the last two numbers of any future year and you will be able to determine which year in the 19 year cycle you are up to.

Some readers may think that this is complicated. It is not. If you would like to learn it, sit down with someone who is slightly mathematically oriented, and you will see that the calculations are, in fact, rather easy.  [Please note that the man on the moon was added to avoid problems of drawing a moon.]

* There is a Yesoma who, boruch Hashem, just got engaged.  If anyone would like to assist in making her chasuna please donate here or contact the author.*

The author can be reached at [email protected]


9 COMMENTS

  1. > The Molad or “new lunation” is the calculation of when the new moon, on average, will appear in Jerusalem, Israel. At that exact moment, on average, it begins when the moon comes between the earth and the sun.

    The two sentences contradict each other.

  2. P’shat is that once a person contemplates and discerns that the moon is then between the earth and the sun, right away afterward, on reflection, it is no longer Yom Kippur Katan, and is already the new molad.

  3. Hidden Calculation:

    The molad is 29 days 1/2 days and 793 chalakim – 28 days = 1 1/2 day and 793 chalakim.
    A chelek is 1/1080 of an hour. 60/1080 = 1/18 min, 3600/1080 = 3 1/3 sec
    793/18 = 44 min and .9 chalokim = 44 min and a chelek.

  4. To get the year in the 19 year cycle divide the current year by 19 and the multiply the remainder by 19.
    See the chart in the Tur after O’CH 428.

  5. georgeg, it is not a contradiction. hazal used the precise number for the average molad as was known by the science of their day. 793 halakim more than 29.5 days. that number is correct to 6 decimal places. today we know that average to 8 decimal places. over the last 1500 years, the molad is off by only about 3 hours.

    However, the molad of any month other than Tishrai does not determine Rosh Hodesh

  6. Currently according to the Taamei Haminhagim kiddush levana protects from a tooth ache. Why?
    In that passage in says that my enemies which includes the Satan should not be able to touch me for the bad.
    There is an explanation in the Hagadah on the rasha of hakheh es shinov, weaken his teeth causing a tooth ache. When taken the gematria of rasha (570) and remove the gematria of shinov (366) we get the gematria of tzadik (204). So, kiddush levana should be a zechus, benefit to us such that this operation should be necessary. Maybe, by 100 years Meshiach has arrived already and a tooth ache will anyway be not be necessary.