When discussing tzitzit that are torn, where is it measured from?
Meaning, do we measure from the first knot, from where the tzitzit hang and where they begin to be intertwined, or, from the last knot, where the tzitzit hang loose?
Essentially it is from the from where the tzitzis hang, which is called “anaf”. There is however an opinion in the Rishonim that it starts from the first after knot (closest to the cloth) called “gedil”. The accepted halacha is from where it hangs, however if there aren’t any other tzitzis to be gotten, one may rely on the lenient opinion, however he wouldn’t make a bracha on the tzitzis.
O:CH 12-1,3, M:B 12-13.