What is the difference between on'yomi and kun'yomi?

On’yomi is the reading that came into Japanese with the character from Chinese. Kun’yomi is the native Japanese word that was attached to the character’s meaning. As a rule of thumb, a kanji standing on its own or followed by hiragana uses kun’yomi, and a compound of two or more kanji uses on’yomi. There are exceptions, so learn readings through words rather than in isolation.

I build Kanji Mnemonics, the app mentioned below, so weigh my suggestions with that in mind.

The two kinds of reading

Take 食 (eat). Its kun’yomi appears in 食べる (taberu, to eat). Its on’yomi, しょく (shoku), appears in 食事 (shokuji, a meal) and 食堂 (shokudō, a canteen). Same character and meaning, two different sounds depending on the word.

Many kanji have more than one on’yomi, because they were borrowed from Chinese at different periods, and some have several kun’yomi for related meanings.

How to guess which one a word uses

• Kanji plus hiragana (okurigana), like 食べる or 高い: almost always kun’yomi.
• A kanji on its own as a noun, like 山 (yama) or 水 (mizu): usually kun’yomi.
• Two or more kanji together, like 食事 or 高校: usually on’yomi.

The exceptions worth knowing

Some compounds mix the two. Japanese even has names for this: 重箱読み (jūbako-yomi, on then kun, as in 台所 daidokoro) and 湯桶読み (yutō-yomi, kun then on, as in 湯桶 yutō itself). Some compounds use kun’yomi throughout, such as 手紙 (tegami, letter). Treat the rule as a first guess, not a law.

How to learn readings without drowning

1. Learn the meaning and shape first. A kanji you recognise is easier to attach sounds to.
2. Add readings through common words. Each new word teaches you a reading in context.
3. Review in both directions, from word to reading and from reading to word.

Where the app fits

Kanji Mnemonics gives each kanji one keyword, one story and one picture for the meaning, and shows its readings and example words so you meet the sounds inside real vocabulary. Two-way flashcards, a Today’s Kanji widget and progress per JLPT level from N5 to N1 help you keep going. It works offline. Lesson 1 is free; Pro is a subscription or a one-time lifetime purchase.

Read next: why you recognise kanji but forget the reading and should you learn to read or write kanji first.