On'yomi and Kun'yomi: The Difference and How to Tell Them Apart

Most kanji have more than one reading, and for many learners of Japanese that is the moment kanji start to feel unfair. 山 is yama when it stands alone, but san in 富士山 and 登山. Japanese children meet the same puzzle. In the Mitsumura Tosho textbook series, for example, the annual teaching plan (in Japanese) puts a unit called “The On and Kun of Kanji” in May of grade 3.

The government’s Jōyō Kanji table (2010, in Japanese) lists readings for 2,136 kanji and states that on readings are shown in katakana and kun readings in hiragana. Most dictionaries and JLPT materials follow the same convention, so once you know it, a kanji entry becomes much easier to read.

This article explains the two kinds of readings, gives rules of thumb for telling them apart, and goes through the cases where the rules do not hold.

Where the two readings come from

Kanji came to Japan from China.

On’yomi (音読み, “sound reading”) is based on the Chinese pronunciation that arrived with the character. The san of 山, the sui of 水 and the ka of 花 are on readings.

Kun’yomi (訓読み, “meaning reading”) is a native Japanese word attached to the character because it means the same thing. The yama of 山, the mizu of 水 and the hana of 花 are kun readings.

So one kanji often carries two readings: one borrowed from outside, and one that is a Japanese word. One way to explain it: the on reading is the sound that came with the character, and the kun reading is what Japanese speakers already called that thing.

Rules of thumb

These rules are guides, not laws, but they cover most of what you will meet.

Does the reading mean something on its own? A Japanese speaker hearing yama knows it means mountain. San alone means nothing in particular. A reading that is a word by itself is usually kun; one that only works inside words is usually on. This test is easier for native speakers than for learners, which is why the next rules help.

Is there okurigana? When a kanji is followed by hiragana that complete a word, as in 生きる (ikiru), 下がる (sagaru) and 歩く (aruku), the kanji is almost always read with its kun reading.

Is it in a two-kanji compound? In compounds such as 山脈 (sanmyaku, mountain range) and 水道 (suidō, water supply), on readings are the norm. There are compounds of two kun readings too, such as 花火 (hanabi, fireworks), so treat this as a strong tendency.

What does it sound like? On readings are short: one or two syllables, and when there are two, the second is usually ん, い, う, き, く, ち or つ. San, sei, gaku and nichi all fit. Kun readings can be longer and come in any shape.

Where the rules break

On readings that feel like words. 絵 (e, picture), 茶 (cha, tea), 肉 (niku, meat), 駅 (eki, station) and 本 (hon, book) are everyday words, so they feel like kun readings. They are all on readings. The Jōyō table gives 肉 and 駅 no kun reading at all, and 茶 only the on readings cha and sa. These are borrowed sounds that became ordinary Japanese words.

Kanji with only a kun reading. The opposite also exists. In the Jōyō table, 畑 (hata, hatake, field) and 箱 (hako, box) have only kun readings. 畑 is a kanji made in Japan, so it never had a Chinese pronunciation.

Kun readings without okurigana. 山, 川 and 花 are kun-read words with no okurigana. The okurigana rule works in one direction only: okurigana suggests kun, but no okurigana does not mean on.

Readings that mix

Some compounds mix the two kinds.

Jūbako reading. The first kanji uses its on reading and the second its kun reading. The name comes from 重箱 (jū-bako, a stacked lunch box). 毎朝 (mai-asa, every morning) and 台所 (dai-dokoro, kitchen) work the same way.

Yutō reading. The reverse: kun first, then on. The name comes from 湯桶 (yu-tō, a hot water pitcher). 手本 (te-hon, model) and 夕刊 (yū-kan, evening paper) are examples.

Readings that do not split

Some words are read as a whole, and the reading cannot be divided between the characters: 今日 (kyō, today), 大人 (otona, adult), 七夕 (tanabata, the star festival), 上手 (jōzu, skillful). These are called jukujikun. The Jōyō table lists them separately, in an appendix, as whole words.

There is no point asking which part of kyō belongs to 今 and which to 日. Learn these as vocabulary.

How to study readings

One approach is to learn one word for each reading, not the readings alone. For 山, learn 山 (yama) and 登山 (tozan, mountain climbing). For 生, learn 生きる (ikiru, to live) and 先生 (sensei, teacher). A bare list of readings is hard to recall. A word gives you something to hang it on, and it tells you where that reading is used.

Do not try to learn every reading at once. The Jōyō table marks some readings as special or of very limited use. Start with the readings that appear in the words you actually meet, and add the rest as they come.

Writing helps too. When you write a reading in hiragana by hand, you have to decide where the kanji ends and the okurigana begins. With 生きる, writing it out makes it clear that the kanji covers i and the okurigana is kiru.

Practicing readings in KanjiN

KanjiN is a kanji app for iPhone and iPad where you answer by handwriting. Instead of tapping a choice, you write on the screen with a finger or stylus.

In the Reading Drill, a sentence shows one kanji in red, and you write its reading in hiragana by hand. Because the kanji appears inside a sentence, you meet the same character with its on reading in one question and its kun reading in another. The Writing Drill works the other way: you see the reading and write the kanji.

In Reading Match, you connect kanji to readings by tapping. On readings appear in katakana and kun readings in hiragana with their okurigana, the same convention dictionaries use.

Besides school grades 1 to 6 and Kanken levels 10 to 5, you can practice JLPT N5 to N3 kanji. Today’s Drill, Today’s Challenge and the 10-question Skill Check are free. A one-time purchase, Unlock Everything, opens every drill, with no ads and no subscription. The first time you use it, the app downloads what it needs to read handwriting, so you need an internet connection then.

For a first session, see Getting Started with KanjiN. For daily habits, see Practical Tips for KanjiN.