In another users answer https://chinese.stackexchange.com/a/2046/38 they said:

一 is pronounced in the first tone when it stands alone. It is pronounced in the fourth tone when it precedes a first, second, or third tone. However, it is pronounced in the second tone when it precedes a fourth tone.

I was surprised to read this and didn't believe it. However, when searching the net I found several places where this is mentioned.

I checked Google translate and it gave me Yīzǎo for 一早 and Yī nián yǐhòu for 一年以后 which is what I always thought it was.

A search on Google for "yīnián" provides me with 106,000 results, but a search for "yìnián" only provides 6,330 results.

Obviously, the examples above only provide partial evidence of correctness. But, is there a reliable, authoritative resource which can confirm the claim that 一 should change to 4th tone?

  • +1 thx for this question that brings even more explainations. Sep 7, 2012 at 8:09
  • 1
    -1: This is stated in essentially every authoritative source about Chinese phonetics. I typed "tone change yi" into google and there were even Google Books results from Chinese textbooks on the first page -- surely that's autoritative enough.
    – Alf
    Sep 7, 2012 at 18:46
  • I wouldn't really use Google as a source. :P
    – Alenanno
    Sep 8, 2012 at 20:11
  • @Jon - It may not come across as a very good question and not worthy of any votes, however I didn't learn my Chinese from western style text books and I am very interested in learning about these things when I come across them. However, I also want to be sure that what I am learning is correct. I have often found that different books and teachers contradict each other.
    – going
    Sep 9, 2012 at 23:50

2 Answers 2


These tone changes, known as tone sandhi, are not indicated according to Hanyu Pinyin rules:

11.1 Only the original tones are indicated; tone sandhi is not indicated.

This is why your Google search for "yìnián" would not necessarily yield more results, because it's still supposed to be written as "yīnián" even when it's pronounced "yìnián".

EDIT: Here's more information on tone sandhi from The Chinese Lexicon: A Comprehensive Survey by Yip Po-Ching, p. 27:

...tone sandhi may also happen by convention in a specific set of words in the lexicon when they are followed by words of different tones. This set includes numericals: 'one', 'seven', 'eight', and the negator 'not'. For example:

on its own or not followed by other tones

when followed by a fourth tone

when followed by other tones

qī/bā on their own or followed by tones other than a fourth

qī/bāqí/bá when followed by a fourth tone

on its own or followed by tones other than a fourth

when followed by a fourth tone


All these tone sandhi applications are actually more or less rule-governed and will not generally be reflected in the pinyin or phonetic notations of the disyllabic words or expressions in question.

  • +1 for pointing out that Pinyin indicates original pronunciation.
    – NS.X.
    Sep 7, 2012 at 19:05
  • 1
    A comment at sinoglot.com/2010/04/once-upon-a-time-we-wrote-yi says "The 七 in 七个 八 in 八个 are said in the first tone by younger speakers in Beijing, but in the second tone by older speakers in Beijing (thus the pronunciation of my professor who is now retired), whereas even younger speakers in Dongbei still use the second tone — not sure where in Dongbei." Personally I have never heard 七月 pronounced "qíyuè" or 八月 pronounced "báyuè".
    – mic
    Dec 26, 2020 at 14:09

What source do you call authoritative? Any Chinese grammar book and handbook series should explain this at some point. In Wikipedia it is also mentioned: https://en.wikipedia.org/wiki/Tone_sandhi#Mandarin_Chinese

Given that there are these tone sandhi, there are two ways to deal with these. You can either write the original tones, or you can write the sandhi. For subsequent third tones (for example 你好), almost nobody will write the sandhi, so almost all dictionaries will write ni3 hao3 instead of ni2 hao3.

Officially you shouldn't indicate the sone sandhi (see http://www.pinyin.info/readings/zyg/rules.html#x4.11), but for 一 and 不 many dictionaries apply the sandhi, while others don't. For example MDBG and 现代汉语词典 write bu4 dui4, while Nciku writes bu2 dui4, while nobody would pronounce it as bu4 dui4 in practice.

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