I've just started to learn Japanese, and I've been looking at the jōyō kanji. Most of the words have on reading and kun reading. I was wondering, which one is most popular and when should I use one over the other?

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    The question title asks about numbers, but the question body talks about ON and KUN in general. Let's keep this question about numbers specifically, as there's already a more general question about ON and KUN: japanese.stackexchange.com/questions/6196
    – user1478
    Apr 26, 2013 at 2:43
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    If you think choosing between on and kun is about popularity, you might have misunderstood the way kanji work. It's like asking whether the "s" or the "k" pronunciation of the letter c is more popular. It depends on the word that it appears in. I think there is some value to learn on and kun readings of kanji one by one, but you should always learn them with the words that they appear in.
    – dainichi
    Apr 27, 2013 at 8:51

2 Answers 2


As a general rule... 

  • You will use ON readings for numbers most of the time when using specific counters. As @summea mentioned, there are numerous times when certain numbers have alternate pronunciations.
  • You will use the KUN readings when specifically using the "generic" counter (一つ, 二つ, 三つ, ...).
  • Then there is a third group of counters that use KUN for the first two, and then switch to ON from there on. I'll have to look up some other examples in my reference book later, but the one I immediately think of is when counting "groups" (グループ).
    • ひとグループ, ふたグループ, さんグループ, よんグループ, ...
  • 5
    – user1016
    Apr 26, 2013 at 15:08
  • @Chocolate: That one is so obvious that I forgot it! :D
    – istrasci
    Apr 26, 2013 at 15:10
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    – Zhen Lin
    Apr 27, 2013 at 7:51
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    @ZhenLin: したがって、6は無理かな?笑
    – istrasci
    Apr 27, 2013 at 17:33
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    [6人]{むり}, [8人]{やり}... 無理矢理や~
    – user1016
    May 5, 2013 at 18:15

There will be times where you'll want to use both ON and KUN readings for numerals in different situations.

For example, when you are counting objects, you might be using KUN readings, like this:


If you were looking at months of the year (January, February, March, etc.) you would most likely be using ON readings, like this:


And do keep in mind that there are a few "weird" numerals (4, 7, and 9) that have their own sets of rules. Sometimes the 4 will be read as し and other times 4 will be read as よん. Sometimes 7 will be read as しち and other times 7 will be read as なな. Sometimes 9 will be read as きゅう other times 9 will be read as く and even other times, 9 will be read even differently (for example, ここのつ for "9 things"; and this can happen for even other numerals! For example: 1, 8, 10, etc.)

As you continue to study, it is helpful to learn both the ON and KUN readings of numerals (even though it is more content to learn) because you will use both, in everyday Japanese.

More information about Japanese numerals can be found on this Wikipedia page, as well.

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    Thanks for the answers guys. I've been learning both ON and KUN and I was just wondering if there any specific times to use on or the other. @snailboat I did start while thinking mainly about numbers but then I got wondering about words in general. Apr 27, 2013 at 4:04
  • @BraedenOrchard Here's at least one general "rule" you could keep in mind when it comes to ON vs KUN readings for words in Japanese (in general): use ON when you have combined kanji (for example: 天気{てんき}, 漢字{かんじ}, 同情{どうじょう}, etc.) and use KUN when you have single kanji or single kanji+hiragana (for example: 緑{みどり}, 書く{か}, 読む{よ}, etc.) This is just a general idea of a "rule", though, and there will probably always be exceptions (especially when reading books... where character readings might be more varied than normal.)
    – summea
    Apr 27, 2013 at 4:14

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