Radicals are only half the system. About 80% of kanji also contain a phonetic component that indicates the sound: 清, 晴, 静, 精 and 請 are all セイ because they all contain 青. The positional rule is that the left or top part carries the meaning and the right or bottom part carries the sound. It holds about two times in three, and it only becomes useful around N4 — because the first hundred kanji a beginner learns are precisely the ones with no phonetic component at all.
Every kanji guide tells you about radicals: 氵means water, 木 means tree, 忄means heart. That is half the system, and it is the half that gets taught.
The other half is that roughly 80% of kanji also contain a part that tells you how the character sounds. Once you can see it, you can guess the reading of characters you have never studied. Almost nobody teaches beginners this, and it is the single biggest shortcut in kanji.
How a Kanji Is Actually Built
Most kanji are 形声文字 (keisei moji, “shape-sound characters”). They pair two jobs:
清 = 氵(water) + 青 (セイ)
The water part says what territory the meaning is in. The 青 part says how it sounds: セイ.
清 is セイ, and it means “clear” — clear like water.
Now watch what 青 does across a whole family:
| Kanji | On’yomi | Meaning part | Means |
|---|---|---|---|
| 青 | セイ | — | blue |
| 清 | セイ | 氵water | clear, pure |
| 晴 | セイ | 日 sun | clear weather |
| 静 | セイ | 争 contend | quiet |
| 精 | セイ | 米 rice | refined, spirit |
| 請 | セイ | 言 speech | to request |
| 情 | ジョウ | 忄heart | emotion |
Six of the seven are セイ. Meet 睛 for the first time and your guess — something to do with the eye (目), pronounced セイ — is correct. You have never studied it.
The Families Worth Knowing
| Sound part | Reading | Family |
|---|---|---|
| 寺 | ジ / シ | 時 time · 持 hold · 詩 poem · 侍 samurai · 待 wait (タイ — the exception) |
| 工 | コウ | 江 river · 紅 crimson · 攻 attack · 功 merit · 貢 tribute |
| 白 | ハク | 拍 clap · 泊 stay overnight · 舶 ship · 迫 press |
| 反 | ハン | 坂 slope · 板 board · 版 edition · 飯 meal · 販 sell |
| 台 | タイ / ダイ | 始 begin (シ — exception) · 怠 idle · 治 govern (ジ/チ) |
| 可 | カ | 河 river · 何 what · 荷 luggage · 歌 song |
| 各 | カク | 格 status · 客 guest (キャク) · 落 fall (ラク) · 略 abbreviate (リャク) |
| 兆 | チョウ | 桃 peach (トウ) · 眺 gaze · 挑 challenge · 逃 escape (トウ) |
Look at 反: 坂, 板, 版, 飯, 販 are all ハン. That is five characters from one 4-stroke component. 飯 is the one people find surprising — a meal has nothing to do with “anti” or “reverse.” It does not need to. The sound part is not contributing meaning at all.
The Rule That Makes It Usable
In a two-part kanji, the part on the left or on top is usually the meaning. The part on the right or on the bottom is usually the sound.
清 = 氵(left, meaning) + 青 (right, sound). 晴 = 日 (left, meaning) + 青 (right, sound). 草 = 艹 (top, meaning) + 早 (bottom, sound, ソウ).
This is why radical study and phonetic study are not competing methods. The radical tells you the topic; the phonetic tells you the pronunciation. Together they let you take a first pass at a character you have never seen.
Where It Breaks
Being honest about the limits is what makes this usable rather than frustrating.
- It only predicts on’yomi. Kun’yomi are native Japanese words attached later and have nothing to do with the character's shape. 時 is ジ from 寺, but its kun’yomi とき is unpredictable.
- Two thousand years of sound change eroded many. 待 sits in the 寺 family but is タイ, not ジ. 客 is キャク, not カク. Expect roughly two in three to hold.
- Some kanji have no sound part at all. Pictographs (山, 川, 木, 日) and compound ideographs (休 = person + tree, 明 = sun + moon) are built entirely from meaning. These are also the earliest and most common characters, which is exactly why beginners meet nothing but exceptions in their first month and conclude the system is arbitrary.
- Simplification broke some links that are still visible in traditional Chinese.
A hint that is right two-thirds of the time on an unknown character is enormously valuable. It is not a rule to trust blindly; it is a first guess that is usually close.
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Take the free JLPT level testHow to Use It From Today
- When you meet a new kanji, split it before you memorise it. Ask: which part is the meaning, which is the sound? That question alone converts a shape into a structure.
- When two kanji share a sound part, learn them together. 晴 and 清 in the same session cost barely more than one of them.
- When a reading will not stick, look for the family. If you keep forgetting that 販 is ハン, the fix is noticing 反 inside it, not another twenty repetitions.
- Do not force it on the first hundred kanji. 山, 川, 日, 木, 人 have no phonetic part. Start applying this from around N4, where compound characters take over.
This is also why kanji accelerates rather than getting harder. Character 1,200 is easier to learn than character 200, because by then almost every new character is assembled from parts you already own. The same compounding is what makes readings settle down over time.
What You Actually Get Inside Kanjijo
Kanjijo is one app that covers every part of Japanese, so you are not stitching together five tools. Here is the full list, as of 2026:
Everything in one app · free to start
- Complete kanji, vocabulary and grammar for all five JLPT levels — N5 through N1, in a fixed order with no gaps.
- Exclusive mnemonics written by hand for every kanji and every vocabulary word — not auto-generated, not borrowed from a public deck.
- SRS reviews that schedule each item right before you would forget it, so 10–15 minutes a day is enough.
- OCR camera scanner — point your phone at a menu, sign, manga panel or receipt and Kanjijo reads the Japanese and turns the words into cards.
- Lock screen widget — a new kanji or word every time you pick up your phone.
- Home screen widget — today’s review count and study item, visible without opening anything.
- Interactive test widget — answer a real question straight from the home screen, no app launch needed.
- JLPT reading practice — graded passages with the exact question types the real exam uses.
- JLPT listening practice — native audio exercises per level, including the trap-heavy formats.
- Full JLPT mock exams — timed, section-scored, so you know your weak section before test day.
- Conversation lessons — natural dialogues with every grammar point actually used in context, not bolted on.
- Shadowing — speak along with native audio and hear yourself against the model.
- Dictation — listen to real everyday Japanese and rebuild the sentence word by word.
Frequently Asked Questions
What is a phonetic component in kanji?
It is the part of a kanji that indicates its pronunciation rather than its meaning. About 80 percent of kanji are 形声文字, shape-sound characters, that pair a meaning component with a sound component. In 清 the 氵 indicates water and the 青 indicates the reading セイ.
Can you guess how a kanji is pronounced?
Often, for the on'yomi. If a kanji contains 寺 it is likely to be ジ (時, 持, 詩), and if it contains 反 it is likely to be ハン (坂, 板, 版, 飯, 販). The hint is right roughly two times in three, because two thousand years of sound change eroded some of the links.
What is the difference between a radical and a phonetic component?
The radical is the component that carries the meaning and determines where a dictionary files the character. The phonetic component carries the sound and usually contributes no meaning at all — which is why 飯, a meal, contains 反, meaning anti or reverse.
How do I tell which part is the sound?
In a two-part kanji, the part on the left or on top is usually the meaning, and the part on the right or on the bottom is usually the sound. So 晴 is 日 for meaning plus 青 for sound, and 草 is 艹 for meaning plus 早 for sound.
Why did nobody teach me this?
Because the first hundred kanji beginners learn are mostly the exceptions. Pictographs such as 山, 川, 日 and 木, and compound ideographs such as 休 and 明, have no phonetic component at all. They are also the oldest and most frequent characters, so a beginner's entire first month suggests the system is arbitrary. Phonetic components become useful from about JLPT N4 onward.
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