On'yomi vs Kun'yomi: When to Use Each Kanji Reading
Open a kanji dictionary and most characters list two kinds of reading. Which one do you use? 山 alone is やま, but 登山 is とざん. The choice isn’t random — there’s a reliable rule of thumb that gets you most of the way.
Two Kinds of Reading
On'yomi (音読み) is the reading borrowed from Chinese when the kanji was imported. Kun'yomi (訓読み) is the native Japanese word that was matched to the character's meaning.
So 山 carries the meaning “mountain.” Its kun'yomi is the native word やま; its on'yomi is the Chinese-derived サン.
The Rule of Thumb
- Kanji standing alone, or with okurigana → usually kun'yomi. 山 = やま, 学ぶ = まなぶ.
- Two or more kanji together (a compound) → usually on'yomi. 登山 = とざん, 学校 = がっこう.
It's a tendency, not a law — there are exceptions (and jukujikun ignore it entirely) — but it predicts the majority of cases.
Examples
How to Study
- Learn both readings with example words, not in isolation — 山 (やま) and 登山 (とざん) together.
- Use the compound-vs-standalone rule as your first guess, then confirm.
- Watch for jukujikun (今日, 大人) that follow neither reading — learn those as whole words.
Teacher's Note
Don't drill readings on bare kanji cards — you'll memorize sounds with no anchor. Always learn a kanji inside a word. The reading then comes with context, and the on/kun choice takes care of itself.
Learn kanji inside real words
Nihongo Pass teaches every kanji with example vocabulary, so on'yomi and kun'yomi come with context — not as a guessing game.
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