I just received a beautiful new tallit with p’til tekhelet. However, I have a query about the length of the tekhelet strings: Each of the four strings extends approximately 12 inches (30 cm) beyond the white strings. Is this how long they should be? The potential problem, of course, is that they may sometimes drag on the ground. I consulted your very interesting website concerning tying tsitsit with tekhelet. I fear that tying tsitsit, with or without tekhelet, goes well beyond my skill set, never mind my dexterity. But in any case, I did not see any reference to the question of whether the tekhelet strings should extend so far.

You are correct that we provide an ample amount of tekhelet such that much is usually
left as extra, and this indeed can be a problem in that the extra strings drag on the floor.
The remedy is to simply cut the strings to the length of the other strings. Indeed you can
cut all the strings down to size keeping in mind two essential parameters of length: the
total length from the first knot by the edge of the Talit to the ends of the strings must be a
minimum of 12 thumb-breadths, and the hanging untied strings section should ideally be
2/3 of the total, the wrapped and knotted part being 1/3 of the total.

The “1/3, 2/3” rule is an ideal that was determined by the Gemara (Men. 39a) to make the
tzitzit look aesthetically pleasing (“noy”). So this ruling is d’rabanan (see Mishna Berura
O.H. 11:66). The Mishna Bereura (O.H. 11:69) explains that all opinions concur that
once the tzitzit are so made, this rule does not mitigate the fulfillment of the mitzvah.
Nevertheless, it is difficult to say ones tzitzit are kosher bidieved, when you can fix them
by simply cutting them down to size.

Acc. to Rambam and Rama, l’chathila, the proportion (1/3,2/3) must be maintained (not
necessarily measured to the mm, but an eye-ball approximation). On the other hand,
Hazon Ish and Maharshal hold that as long as the gdil (knotted area) is 4 thumb-breadths,
the anaf (hanging strings) can be 8 or more thumb-breadths (i.e., the proportion need not
be maintained).

Bottom line: it seems it would be advantageous to cut your strings to meet the 1/3,2/3
proportion as there is a certain benefit according to the Rambam and Rama, and the
Hazon Ish and Maharshal are merely providing a leniency without any advantage.

There are those who recommend that one not use metal to cut the strings but rather ones
teeth (or ceramic or plastic scissors) – but it is not forbidden to use metal, nor does the use
of metal invalidate the strings. If you do decide to cut your strings, I personally have
found that when you cut them all to be the exact same length they are not as aesthetically
pleasing as when they are cut with slightly differing, but close, lengths.

– Mois Navon.