Phonetic Components: Guess a Kanji's On'yomi

Short answer: Many kanji are made of a meaning part plus a sound part, and the sound part often tells you the on’yomi. 晴, 清 and 精 all contain 青 and are all read セイ; 坂, 板 and 版 all contain 反 and are read ハン or バン. Once you know a few dozen common sound parts, you can often guess the on reading of a kanji you have never seen.

This is the most useful reading trick in kanji study, and many learners only find out about it after a year or two. Here is how it works and where it fails.

The kinds of kanji

Traditional Chinese character study sorts kanji into a few types. The ones you meet most:

• Pictographs (象形文字): simple pictures, like 山 (mountain) or 木 (tree).
• Simple ideographs (指事文字): marks for abstract ideas, like 上 (above) and 下 (below).
• Compound ideographs (会意文字): two meaning parts combined, like 休 (rest): a person by a tree.
• Phono-semantic compounds (形声文字): a meaning part plus a sound part.

The last group is by far the largest. That is why the trick works so often.

How a sound part works

In a phono-semantic kanji, one part narrows down the meaning and the other gives a sound. The sound part was chosen because, in Chinese, it was read the same or similarly. Japanese on’yomi come from those Chinese readings, so the pattern carries over in many cases.

Take the 青 family. 青 itself means blue and is read セイ (and ショウ).

Kanji	Meaning part	Meaning	On’yomi
青	(itself)	blue	セイ, ショウ
晴	日 sun	clear up	セイ
清	氵 water	pure	セイ, ショウ
精	米 rice	refined	セイ, ショウ
情	忄 heart	feelings	ジョウ, セイ

The meaning part tells you what area the kanji is about (weather, water, rice, emotion). The sound part tells you the reading. 情 shows the limit: its common reading is ジョウ, as in 情報 (じょうほう, information), though セイ is listed too.

More families worth knowing

反 (ハン)

Kanji	Meaning	On’yomi
反	anti-	ハン, ホン, タン
坂	slope	ハン
板	plank	ハン, バン
版	printing block	ハン
飯	meal	ハン

同 (ドウ)

Kanji	Meaning	On’yomi
同	same	ドウ
銅	copper	ドウ
洞	den	ドウ
胴	trunk	ドウ

古 (コ)

Kanji	Meaning	On’yomi
古	old	コ
固	harden	コ
個	individual	コ, カ
湖	lake	コ

包 (ホウ): 包 (wrap), 抱 (embrace), 泡 (bubble) and 砲 (cannon) are all read ホウ.

Readings in these tables come from the Kanji Guide kanji pages.

Where the trick breaks

Phonetic components are a hint, not a rule:

• Voicing changes. ハン can become バン, as in 看板 (かんばん, signboard). コウ can become ゴウ.
• Related sounds. Some families share a vowel or a consonant, not the whole reading.
• Lost connections. Sound changes in Chinese and Japanese over centuries broke some families. A kanji may contain a sound part and read quite differently.
• Hidden parts. Simplified forms in modern Japanese sometimes changed the sound part so it is no longer easy to see.
• Kun’yomi. The trick says nothing about kun readings, which are native Japanese words.

So use it to make a first guess, then check the word in a dictionary.

How to use this in your study

1. Notice families as you go. When a new kanji contains a part you already know as a full kanji, check whether they share a reading.
2. Group family members in reviews. Studying 晴, 清 and 精 together makes the shared セイ stick.
3. Learn the reading through a word. 快晴 (かいせい, clear weather), 清潔 (せいけつ, clean), 精神 (せいしん, mind). The family gives you the sound; the word gives it a use.
4. Use it when reading. Facing an unknown kanji, spot the sound part and try that reading. See how to read kanji without furigana.

Phonetic components and stories

Mnemonic stories, like the ones in Kanji Guide, help you remember meanings. Phonetic components help with readings. The two work well together: the story tells you what 晴 means, and the 青 inside it reminds you that it is probably read セイ.

Where to go next

For background on the two reading types, see on’yomi vs kun’yomi explained. To compare family members yourself, open 青, 晴 or 反, or start in the study app.