At what age must one get married?
It is a Mitzvah upon every person to marry a woman at 18 years of age, and one who precedes and marries at 13 years of age [has fulfilled] the Mitzvah Min Hamuvchar. In any event, one may not pass 20 years of age without getting married. One who has passed the age of 20 and does not wish to get married, then in previous times the Beis Din would coerce him to marry in order to fulfill the Mitzvah of having children. However in today’s times one is no longer coerced by Beis Din to get married.
Child marriages-Marrying prior to 13 years old: Prior to 13 years of age a boy may not get married, as it is considered like promiscuity.
Delaying marriage past 20 due to learning Torah: If one is involved in Torah learning and toils in it, and fears to marry a woman lest he be required to toil after sustenance and thus nullify his Torah learning, then it is permitted for him to delay getting married even past the age of 20 [for as long as he wants]. This however is only on condition that his inclination does not give him erotic thoughts and he is able to thus learn without thoughts of sin. If however he is troubled by erotic thoughts and is thus unable to properly learn due to it then he is to first get married and then learn Torah with purity of mind. Furthermore, this allowance of delay is only for a person who has the intellectual capacity to learn and remember the entire Torah, which includes all of the Jewish laws, Biblical and Rabbinical, together with all their details and reasons. If however he does not have the intellectual capability to learn and remember all of the Torah, then he must get married prior to the age of 20.
Practically, by what age must Yeshiva Bochurim today get married by?
Based on above, in today’s times most Yeshiva students must get married before the age of 20, as most students are not born with the intellectual ability to learn and remember the entire Torah. Furthermore, even those that are able to reach this state of learning, many are troubled by erotic thoughts. Nonetheless, many communities are accustomed to delay marriage past 20 due to maturity reasons, and hence the child is considered incapable of getting married beforehand due to reasons of immaturity. Despite this, it is possible to educate children to be mature and ready for marriage at an earlier age, and hence fulfill the Mitzvah of Peru Urevu according to Biblical requirement, as is done in many Chassidic communities to marry at 18.
The Chabad custom: The Rebbe was very adamant to change the marriage age so Bochurim would marry prior to 20 years old, and so have ruled the vast majority of Chabad Rabbanim. [Click here to view the letter ]
A story of How the Rebbe told me to marry young
By: Rabbi Y Goldstein
After having finished Shiur Gimel in a prominent Chabad Yeshivah I decided to spend my next year learning Semicha in 770. I turned 21 that year. I was learning assiduously in 770 in the process of doing Semicha, and spent my time learning day and night. At that time I began writing Pilpulim in Halacha which were subsequently published in the bi-weekly Kovetzim. One week I had published a deep Halachic Pilpul in regards to the Marriage age and if in truth there is any allowance to delay marriage past the age of 20. The conclusion of the lengthy discussion made evident that there is no longer a clear Halachic allowance to delay marriage past 20. Prior to sending the surprising and controversial matter to be published, I discussed the Pilpul and its conclusion with a few Rabbanei Anash and Roshei Yeshivas. They agreed with my conclusion but stated that if one is not mature enough [or the system denies him the ability to be ready for marriage] then he is Onus and hence Halachilcy exempt. With these words I concluded the Pilpul.
Very shortly after the Pilpul was published I sat down to write a weekly Duch to the Rebbe about my Friday Mivtzaim route. I placed the letter in Igros Kodesh and randomly opened to a page. [See appendix 1 below] On that page I noticed a letter which the Rebbe wrote to a Bochur urging him to begin his quest for Shiduchim and how the matter is relevant to him for both physical and spiritual reasons. I did not give much attention to the letter as I was not mentally prepared for Shidduchim at that point, and mainly because I wrote nothing about that subject. Surprisingly enough that night one of my Chavrusas told me that someone asked him about me for a possible Shidduch. I of course refused and told him it’s out of the question. I then remembered however how that same night I opened to a letter in which the Rebbe gave a Bochur a clear directive to begin Shidduchim. Nu! In the end of the day perhaps it was just a load of coincidences and I brushed it off my mind. The Shadchan however did not, and continued to approach me throughout the week about the issue.
After deep deliberation, and discussion with my Mashpia, I decided to sit down and write a letter to the Rebbe about the entire issue. The question was very simple: Should I begin Shidduchim or not? The main issue was my age and the fact that I was in the midst of Semicha and had a brilliant future of learning ahead of me. At that point starting shidduchim freshly after turning 21 was not very popular, to say the least, for a good Chassidisher Bochur.
The answer I opened to in Igros Kodesh [See appendix 2] will remain with me the rest of my life.
The Rebbe stated clearly and unequivocally: “I already wrote to you once about this topic, your are to begin to seek a Shidduch immediately as this matter pertains to your physical and spiritual wellbeing.”
I, obviously was in a state of shock not having expected anything of the sort. I proceeded to discuss the matter in depth with my Mashpia, who I must admit was not most enthusiastic about the idea of writing in Igros Kodesh. Nevertheless in this case it was clear as day that the Rebbe has given me instructions and he told me as whatever his opinion may be “Ein Achareiy Divrei Hamelech Klum”. I was then advised to proceed to discuss the matter with the Hanhalah of the Yeshivah, 770, and follow based on their advice. The majority opinion in the Hanhalah was to follow through with the Rebbes instructions as I opened to, while minority claimed I am too young and it is out of question. I made a decision based on the majority opinion in Hanhala and decided to write my decision into the Rebbe and place it into Igros Kodesh. In the letter I also wrote that there was one opinion amongst the Hanhala which claimed that I was too young and disagreed with my decision.
The letter I opened too [see appendix 3] was as clear as day in regards to encouraging me to marry young and negating the opinion which put it down. The Rebbe stated “If only it should be that also the Ashkenazim would marry at a very young age as do the Sefaradim”.
Appendix 1: 1st letter [Igros Hakodesh 12]
Appendix 2: 2nd letter [Igros Hakodesh 14]
Appendix 3: 3rd letter-Igros Hakodesh 20
 Michaber 1/3
 Meaning he must marry prior to reaching 20.
 Rama ibid
 Michaber ibid
 Rama ibid
 Beis Shmuel 1/5
 Michaber ibid
The reason: As although the one must stop learning in order to fulfill a positive command, this only refers to a positive command that can be fulfilled momentarily, as one can shortly afterwards resume his Torah learning. However if one were to get married, then he would be unable to continue learning at all, as he must now sustain his family. [Admur Hilchos Talmud Torah Kuntrus Achron 3/1]
 Admur Hilchos Talmud Torah 3/1-2; Michaber 1/4; Beis Shmuel 1/5; Vetzaruch Iyun why it was not mentioned here by Michaber!!!
 Admur Hilchos Talmud Torah 3/1
The reason: As only if one learns and remembers the entire Torah does he fulfill the Mitzvah of Yedias Hatorah which is even greater than the Mitzvah of Peru Urevu. [Admur Hilchos Talmud Torah Kuntrus Achron 3/1]
 The reason: As the Mitzvah of learning Torah is only greater than Peru Urevu if one can fulfill the Mitzvah of Yedias Hatorah, which is to learn and remember the entire Torah. If however one cannot do so, then although he can still fulfill the Mitzvah of Vehigisa Bo Yomam Valayla, nevertheless this does not push off the Mitzvah of Peru Urevu. [Admur ibid]
 Igros Kodesh 13/23; 20/175; Letter 5,974