On'yomi and Kun'yomi: Kanji Readings Explained

The short explanation

On’yomi are readings connected historically with pronunciations borrowed from Chinese. Kun’yomi connect a kanji with a native Japanese word.

These labels help you describe what happens in a word. They are not a dependable shortcut for guessing every reading. Japanese has old sound changes, counters, names, and common exceptions, so the safest unit to learn is a complete word.

On’yomi are normally shown in katakana in dictionaries and learning data. Kun’yomi are normally shown in hiragana. That display convention does not mean the word itself must be written in katakana.

One kanji, two useful contexts

山 — mountain

• 山(やま) uses the kun’yomi やま.
• 富士山(ふじさん) uses the on’yomi サン.

The useful fact is not merely “山 has two readings.” It is that the word 山 is やま, while the name 富士山 is ふじさん.

人 — person

• 人(ひと) uses the kun’yomi ひと.
• 日本人(にほんじん) uses ジン.
• 三人(さんにん) uses ニン.

Even two on’yomi can have different jobs. Learn 日本人 and 三人 as complete words rather than trying to choose between じん and にん from a single simple rule.

月 — moon or month

• 月(つき) means “moon” and uses a kun’yomi.
• 月曜日(げつようび) means “Monday” and uses ゲツ.
• 一月(いちがつ) means “January” and uses ガツ.

The month names are especially good evidence that a character does not have one fixed sound.

Compounds are useful clues, not rules without exceptions

Words made from two or more kanji often use on’yomi, while a kanji used as a native word with hiragana after it often uses kun’yomi. That is a helpful pattern to notice.

It is not a rule you should use blindly. 今日(きょう), “today,” and 大人(おとな), “adult,” are common words whose readings are best learned whole. Counters can also change sounds: 一人 is ひとり, while 三人 is さんにん.

Names introduce still more readings. A beginner dictionary or verified course material should guide you; do not assume a familiar everyday reading will predict a person’s name.

What should I memorize?

1. Learn the kanji’s core meaning.
2. Learn one or two high-value words.
3. Notice which reading those words use.
4. Add another reading when a new word requires it.

For 学, begin with 学生(がくせい) and 学校(がっこう). Later, 学ぶ(まなぶ) gives you a useful kun’yomi. That sequence is more memorable than an isolated list.

A small review habit

When you review a card, cover the reading and ask:

• What central idea does this character carry?
• Which useful word do I know with it?
• How is the kanji read in that word?

If you remember the word but forget the label “on’yomi” or “kun’yomi,” the vocabulary knowledge is still the important achievement. The labels become easier as you see more examples.

Next: Kanji Stroke Order