Halachah 1 — Eight Sinaitic Requirements for Tefillin
There are eight requirements for the manufacture of tefillin, all of which are halachot transmitted to Moshe at Sinai.
Failure to fulfill any one of them renders the tefillin invalid.
They are:
- Squareness,
- Shin embossed on the batim,
- Wrapping in fabric,
- Winding of hair,
- Sewing with sinews,
- Presence of a ma’aboret for straps,
- Black straps,
- A knot shaped like a dalet.
Halachah 2 — Squareness and the Shin
The tefillin must be perfectly square and sewn square, with equal diagonals and angles.
The leather of the head‑tefillin must have:
- a three‑headed shin on the right side,
- a four‑headed shin on the left side.
These shapes are molded into wet leather over a wooden block.
Halachah 3 — Formation of the Head Tefillin
Leather is soaked, pressed over a carved mold with grooves, and shaped until it forms:
- four distinct compartments,
- with the shin symbols clearly formed.
After drying, each of the four parchments is placed in its own compartment, the base folded under, and the batim sewn shut, leaving space for the ma’aboret.
Halachah 4 — Formation of the Arm Tefillin
The arm‑tefillin are molded over a rectangular block forming one compartment.
The four passages are inserted, the leather folded underneath, sewn closed, and a ma’aboret formed for the strap.
Halachah 5 — Order of Parashiyot in the Head Tefillin
The order of the four passages in the head‑tefillin, from the wearer’s right to left, is:
- V’hayah im shamo’a
- Shema
- V’hayah ki y’viacha
- Kadesh li
If the order is altered, the tefillin are invalid.
Halachah 6 — Parashiyot of the Arm Tefillin
The passages of the arm‑tefillin are written:
- on a single parchment,
- in four columns,
- in the Torah’s textual order.
If written on four separate parchments and placed together, they are valid even without gluing.
Halachah 7 — Rolling the Parashiyot
All parchments must be rolled from end to beginning, so that when opened, the text may be read in its proper order.
Halachah 8 — Wrapping in Fabric and Hair
Before insertion:
- the parchments are wrapped in cloth,
- and hair is wound around them.
The hair must be from a kosher animal, even if the animal was not ritually slaughtered or was a treifah.
The custom is to use hair from a calf’s tail.
Halachah 9 — Sewing with Sinews
Tefillin may be sewn only using sinews from kosher animals.
Sinews from animals that died naturally or were treifah are permitted.
They are softened, spun, and used as sewing threads.
Halachah 10 — Stitching the Batim
The batim must be sewn square.
The custom is:
- three stitches on each side (twelve total), though ten or fourteen are acceptable.
Each stitch must pass completely through.
Halachah 11 — Separation of Compartments
The grooves separating the four compartments must be clearly visible.
Ideally, each groove reaches the stitching.
If separation is discernible but incomplete, the tefillin remain valid.
A sinew is customarily passed through each groove externally to emphasize division.
Halachah 12 — Dimensions of the Straps
Straps must be at least a barley‑corn wide.
- Head straps must reach the navel or slightly above.
- Arm straps must reach far enough to wrap the forearm and three times around the middle finger.
Longer straps are acceptable.
Halachah 13 — Knots of the Tefillin
The head‑tefillin knot must form the shape of a dalet.
The arm‑tefillin knot must form the shape of a yud, allowing adjustment.
These knots cannot be adequately described in writing and must be learned visually.
Halachah 14 — Color of the Straps
The outer surface of both straps must be black, by law from Sinai.
The inner side may be pale or white but not red.
It is aesthetically preferred that all tefillin components be black.
Halachah 15 — Source and Processing of the Leather
Leather must come from a kosher animal, beast, or bird.
The straps must be processed with explicit intent for the mitzvah.
The batim leather need not be processed and may even be made from pressed matzah, as commonly practiced.
Halachah 16 — Who May Manufacture Tefillin
Tefillin must be made only by a Jew, as their construction is akin to writing sacred text.
If made or sewn by a gentile—or any person disqualified from writing—they are invalid.
Halachah 17 — Changing the Status of Tefillin
One may not downgrade head‑tefillin into arm‑tefillin.
One may upgrade arm‑tefillin into head‑tefillin, provided they were never worn.
This is done by reshaping the leather to create four compartments.
Halachah 18 — Torn Stitches
If:
- two adjacent stitches tear, or
- three stitches tear anywhere,
the tefillin are invalid if old.
If new and structurally intact, they remain valid.
The distinction depends on the strength of the leather.
Halachah 19 — Torn Straps
A torn strap may not be repaired.
It must be entombed and replaced.
Remaining strap material is valid only if it still meets minimum requirements.
One must always ensure the black side faces outward when wearing tefillin.
