I am referring to the Origin of zhuyin symbols table on Wikipedia. Under Rhymes and Medials the following 3 entries confuse me:

Zhuyin IPA Pinyin
i i/y
u u/w
y ü/yu/u

Why are there multiple Pinyin symbols for the same IPA sound? Are there any general rules as to which one of these symbols should be preferred?

  • 1
    If you're asking from a learning or teaching perspective, you can check this article I wrote about this.
    – Olle Linge
    Commented Nov 8, 2012 at 1:42
  • The answer to the last question "are there any general rules" is a definite Yes; pinyin is very clear about which letters to use for specific sounds. It depends on various conditions. Commented Apr 14, 2021 at 12:55

2 Answers 2


You can find the explanation in page for Pinyin on wikipedia:

Note on y and w

y and w are equivalent to the semivowel medials i, u, and ü (see below). They are spelled differently when there is no initial consonant in order to mark a new syllable: fanguan is fan-guan, while fangwan is fang-wan (and equivalent to fang-uan). With this convention, an apostrophe only needs to be used to mark an initial a, e, or o: Xi'an (two syllables: [ɕi.an]) vs. xian (one syllable: [ɕi̯ɛn]). In addition, y and w are added to fully vocalic i, u, and ü when these occur without an initial consonant, so that they are written yi, wu, and yu. Some Mandarin speakers do pronounce a [j] or [w] sound at the beginning of such words—that is, yi [i] or [ji], wu [u] or [wu], yu [y] or [ɥy],—so this is an intuitive convention. See below for a few finals which are abbreviated after a consonant plus w/u or y/i medial: wen → C+un, wei → C+ui, weng → C+ong, and you → C+iu.

Well, this note is so detailed, I really feel it difficult to add something… maybe it can be concluded as this:

When [i] and [u] sounds appear at the beginning of a Chinese character, they're written as y and w, in other cases they're written as i and u.


I am very unfond of pinyin, but it makes more sense looking at it like:

  • (y)i
  • (w)u
  • (y)ü

since the () is situational. Again with regards to the semivowels, these specifically merely change if they're beginning a word/syllable. It's easier to say & to read this way. It's a helpful feature.

That said, there are plenty of mapping issues within the entire vowels system for pinyin, and the general solution is to teach each as exceptions in pronunciation in "special cases" or ignore the point. Neither seems particularly efficient however, especially from a learning perspective.

Zhuyin maps 1-to-1, and personally I just made my own romanisation to match it and maintain accuracy. Regardless, how you speak is priority over spelling matters, try to ingrain good examples of different syllables for reference when needed in new contexts.

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