Where do the tone marks go?

Tone marks in Hanyu Pinyin always go over vowels, not consonants. But even those familiar with Hanyu Pinyin are often uncertain about which in a string of vowels takes the tone mark. If, for example, you are given "huai4" -- is it hùai, huài, or huaì? (Answer: the second choice.)

Fortunately there are no ambiguities to worry about, even where there are several vowels in a row. Various complicated rules explain the placement. Fortunately, in application they boil down to a few very simple guidelines:

The possible vowel combinations are listed below, with the vowel that receives the tone marked as second tone.

  a e i o u ü
a     ái áo    
e     éi      
i iá, iáo ié   ió iú  
o         óu  
u uá, uái ué uó    
ü   üé        

Note: Early versions of Hanyu Pinyin also used . But since it never was combined with other vowels it is not included here. (It has since been supplanted by ei.)

See also converting tone numbers to tone marks.