The phonology of Standard Chinese has historically derived from the Beijing dialect of Mandarin. However, pronunciation varies widely among speakers, who may introduce elements of their local varieties. Television and radio announcers are chosen for their ability to affect a standard accent. The sound system has not only segments—i.e. vowels and consonants—but also tones, and each syllable has one. In addition to the four main tones, there is a neutral tone that appears on weak syllables.

This article uses the International Phonetic Alphabet (IPA) to compare the phonetic values corresponding to syllables romanized with pinyin.

The sounds shown in parentheses are sometimes not analyzed as separate phonemes; for more on these, see § Alveolo-palatal series below. Excluding these, and excluding the glides [j], [ɥ], and [w], there are 19 consonant phonemes in the inventory.

Between pairs of plosives or affricates having the same place of articulation and manner of articulation, the primary distinction is not voiced vs. voiceless (as in French or Russian), but unaspirated vs. aspirated (as in Scottish Gaelic or Icelandic). The unaspirated plosives and affricates may however become voiced in weak syllables (see § Syllable reduction below). In pinyin, an unaspirated/aspirated pair such as /p/ and /pʰ/ is represented with b and p respectively.

More details about the individual consonant sounds are given in the following table.

All of the consonants may occur as the initial sound of a syllable, with the exception of /ŋ/ (unless the zero initial is assigned to this phoneme; see below). Excepting the rhotic coda, the only consonants that can appear in syllable coda (final) position are /n/ and /ŋ/ (although [m] may occur as an allophone of /n/ before labial consonants in fast speech). Final /n/, /ŋ/ may be pronounced without complete oral closure, resulting in a syllable that in fact ends with a long nasalized vowel. See also § Syllable reduction, below.

The consonants listed in the first table above as denti-alveolar are sometimes described as alveolars, and sometimes as dentals. The affricates and the fricative are particularly often described as dentals; these are generally pronounced with the tongue on the lower teeth.

The retroflex consonants (like those of Polish) are actually apical rather than subapical, and so are considered by some authors not to be truly retroflex; they may be more accurately called post-alveolar. Some speakers not from Beijing may lack the retroflexes in their native dialects, and may thus replace them with dentals.