Mezuzah: what to buy, where to hang, what to say
From choosing a kosher klaf to knowing which doorposts need a mezuzah—everything you need before you pick up a hammer.
Mezuzah: What to Buy, Where to Hang, What to Say
A mezuzah is a hand-written parchment scroll affixed to the doorposts of a Jewish home, fulfilling the commandment in Devarim 6:9. Before standing before a beit din, you should be able to walk into any Jewish home, point to the doorposts that require one, and explain why it sits where it sits and what was said when it was hung.
The decorative case most people photograph on Instagram is not the mitzvah. The mitzvah is the small piece of parchment rolled up inside.
What is actually inside the case
The klaf (parchment) carries two Torah passages written in Hebrew by a trained sofer: Shema (Devarim 6:4–9) and V'haya im shamoa (Devarim 11:13–21). On the reverse side, the sofer writes the divine name Sha-dai, and the letter shin (ש), the first letter of that name, is usually visible through a small window in the case.
A kosher klaf requires treated animal-skin parchment, specific ink, precise letter formation, and the correct order of writing. The Shulchan Aruch (Yoreh De'ah 285) lays out these scribal requirements in detail. A printed scroll, a photocopy, or a machine-produced imitation does not fulfill the mitzvah at all. You can hang the most beautiful hand-painted ceramic case from Tzfat on your doorpost, but if the klaf inside is printed, halachically your doorway is bare.
This is the first thing to internalize: when someone says "I bought a mezuzah," the only question that matters is who wrote the klaf.
How to buy a kosher mezuzah without being misled
Buy only from a reputable Judaica store or directly from a sofer who provides a hechsher from a recognized Orthodox authority. Ask the seller plainly: "Is this klaf kosher, and who certified it?" A trustworthy seller will show you the certification without hesitation.
Price is a useful filter. A single kosher klaf typically runs $30–$80, and mehudar (higher-quality) scrolls cost considerably more because of the hours a sofer spends writing them. If you see a "mezuzah" for $5 at an airport gift shop or a souvenir stand on Ben Yehuda, it is almost certainly a printed facsimile. Tourist shops, general online marketplaces, and non-specialist stores are not where you buy klafim.
A few practical rules:
Pre-rolled, sealed klafim from a reliable sofer or Judaica store are fine. Ask to see the certification before paying.
If you receive a mezuzah as a gift, have it checked (bedikah) by a certified sofer before affixing it. You cannot assume the giver verified it.
Keep the case separate in your mind from the scroll. You can own ten lovely cases and only two kosher klafim; you only have two mezuzot.
The Rambam (Mishneh Torah, Hilchot Mezuzah 5:4) urges extra care with this mitzvah, noting that every time a person enters or leaves the home, they encounter the unity of Hashem and are drawn back from distraction. That is why cutting corners here feels so wrong once you understand what you are doing.
Which doorways actually require a mezuzah
The Torah obligation applies to the doorways of your home, but halacha defines "doorway" precisely. Four conditions must be met:
Two doorposts (one on each side)
A lintel across the top
Minimum height of 10 tefachim (roughly 80 cm / 32 inches)
Minimum width of 4 tefachim (roughly 32 cm / 13 inches)
In practice, this means your front door, bedroom doors, living room, kitchen, dining room, home office, and most hallways with proper doorposts all require a mezuzah. For a standard apartment in Jerusalem or Tel Aviv, you are usually looking at between five and ten mezuzot once you count every qualifying opening.
Doorways that do not get a mezuzah include bathrooms and lavatories (a mezuzah cannot be present where a person is unclothed or relieving themselves), small storage closets, and archways that lack real doorposts. Some doorways are halachically debated: a gate to an enclosed courtyard, a laundry room, a doorway between two rooms that both already have mezuzot elsewhere. Yoreh De'ah 286 covers much of this, but the honest answer for a conversion candidate is: ask your sponsoring rabbi to walk through the apartment with you, or send him photos. These questions come up constantly and have clear answers in each case.
Exact placement: right side, upper third, slight tilt
The mezuzah goes on the right doorpost as you enter the room. "Entering" is determined by the normal direction of traffic: for a front door, right as you walk into the apartment; for a bedroom, right as you walk into the bedroom from the hallway.
Height: the mezuzah is placed in the upper third of the doorpost, ideally right at the start of that top third. If the doorpost is extremely tall, place it no higher than shoulder height so you can reach it comfortably when passing.
The angle has a famous backstory. The Talmud (Menachot 33a) records a dispute: Rashi held the mezuzah should be vertical, Rabbeinu Tam held it should be horizontal. The Rema (Yoreh De'ah 289:6) rules for Ashkenazim that we hang it on a diagonal, the top tilted inward toward the room, as a compromise honoring both opinions. Sephardic practice generally follows the Rambam and places the mezuzah vertically. Ask your rabbi which custom applies to you; it depends on the community you are joining.
The mezuzah must be firmly affixed. Nail it, screw it, or secure it with strong adhesive. The verb used in the blessing is likboa, "to fix permanently." A mezuzah dangling from a thumbtack that falls off when the door slams is not considered properly installed. For renters, strong double-sided mounting tape is widely accepted, but confirm with your rabbi.
The blessing and the moment of hanging
Immediately before affixing the mezuzah, you recite:
Baruch Atah Hashem, Elokeinu Melech ha'olam, asher kid'shanu b'mitzvotav v'tzivanu likboa mezuzah.
Blessed are You, Hashem our God, King of the universe, who has sanctified us with His commandments and commanded us to affix a mezuzah.
If you are hanging several mezuzot in one session, moving into a new apartment for example, you recite the blessing once before the first one and then hang the rest without repeating it. The single blessing covers them all, provided you do not have a long interruption between them. Hang the front door first if practical.
A note specifically for conversion candidates: before your giyur is complete, your obligation in mitzvot is not identical to that of a born Jew. Whether you should recite the blessing, affix mezuzot in your current home, or wait is a question for your sponsoring rabbi. Many rabbis encourage candidates to build an observant household gradually and to hang mezuzot (sometimes without the blessing) as part of that process. Do not improvise this decision. Ask.
After the mezuzah is up, there is a lovely custom to touch it with your fingers when passing through the doorway and then kiss the fingers, a small moment of recognizing that Hashem is present at the threshold. It is a minhag, not an obligation, but almost every observant Jew does it.
Common questions
Can I reuse an old case and just put a new klaf inside?
Yes. The case has no halachic status; it only protects the scroll. Slide a certified kosher klaf into any case you own, make sure the klaf is rolled correctly (from the end of the text toward the beginning, so Shema is on the outside) and that the shin faces outward, and affix it. If you are unsure how to roll it, the sofer or Judaica store will do it for you.
How often does a mezuzah need to be checked?
The Shulchan Aruch (Yoreh De'ah 291:1) requires that mezuzot be checked twice every seven years. In practice, many people check every three to four years, and immediately after any flood, fire, extended humidity, or visible damage. Ink can fade, letters can crack, and a single invalid letter can render the klaf pasul (invalid).
I moved into an apartment with mezuzot already on the doors. Can I use them?
Do not assume they are kosher. Take them down carefully, bring them to a sofer for inspection, and only re-hang them if they pass bedikah. Many apartments in Israel are passed between Jewish tenants with mezuzot left in place as a kindness, but the previous tenant's standards may differ from yours, and parchment degrades over time. There is also an established custom of compensating the previous tenant for mezuzot left behind; your rabbi can advise.
Does a garden gate or courtyard entrance need a mezuzah?
A gate with real doorposts, a lintel, and the minimum dimensions, leading into an enclosed area used for living, may well require a mezuzah according to many opinions, though usually without a blessing because of the halachic uncertainty. Shared building entrances, parking areas, and purely external gates are more complicated. Send your rabbi a photo and a description of how the space is used, and let him rule.