Kanji Root Families: The Most Productive Kanji by the Numbers¶

Hard data from the 27,950-compound Kanji Database - which kanji combine with the most partners, and what that means for learning

Part of the Roots of Japanese project. See also: Catalog | Sound Roots | Verb Roots

How This Data Was Collected¶

This analysis is based on direct queries to the Kanji Database (kanjidatabase.com), created by Tamaoka, Makioka, Sanders & Verdonschot (2017).

Database specs: - Corpus: 11 years of Mainichi Newspaper articles (2000-2010) - Total morphemes: 282,816,611 tokens - Unique compound words: 27,950 two-kanji jukugo - Kanji covered: 2,136 Jōyō kanji

The metric: "Kanji Productivity" (type frequency) = the number of unique two-kanji compound words a given kanji appears in.

Key distinction: - Left Kanji Prod. = compounds where this kanji is the first element (prefix-like) - Right Kanji Prod. = compounds where this kanji is the second element (suffix-like)

The Top 30 Most Productive Kanji¶

These are the kanji that appear in the highest number of unique two-kanji compounds. Every single one is a high-leverage learning target.

Rank	Kanji	Core Meaning	Left	Right	Total
1	大だい	big, great	57	228	285
2	人ひと	person, people	173	96	269
3	一いち	one, first	19	231	250
4	水みず	water	113	121	234
5	手て	hand	114	97	211
6	地ち	earth, ground	116	81	197
7	気き	spirit, energy	129	64	193
8	上うえ	up, above	84	101	185
9	物もの	thing, object	144	39	183
10	子こ	child	156	27	183
11	中なか	middle, in	80	102	182
12	本ほん	book, origin	61	116	177
13	下した	down, below	78	99	177
14	国くに	country	78	95	173
15	金きん	gold, money	85	88	173
16	出しゅつ	exit, put out	77	91	168
17	小しょう	small	19	149	168
18	内ない	inside	60	107	167
19	生せい	life, birth	90	74	164
20	不ふ	not, un-	161	0	161
21	行こう	go, do	119	40	159
22	無む	without	153	4	157
23	外そと	outside	64	92	156
24	文ぶん	writing, culture	87	69	156
25	心こころ	heart, mind	107	47	154
26	名めい	name	76	78	154
27	風かぜ	wind, style	85	69	154
28	目め	eye	109	44	153
29	学がく	study, learn	91	61	152
30	長ちょう	long, chief	82	68	150

Minimum total to crack top 30: 150 compounds

The Left-Hand vs Right-Hand Split¶

The database reveals a striking asymmetry: some kanji strongly prefer one side.

The Most "Prefix-like" (Left-Dominant)¶

These kanji appear most often as the first element of a compound:

Rank	Kanji	Left	Right	Ratio L:R	English Analogy
1	人ひと	173	96	1.8:1	anthropo-
2	子こ	156	27	5.8:1	child-, infant-
3	物もの	144	39	3.7:1	object-, thing-
4	気き	129	64	2.0:1	spirit-, atmos-
5	行こう	119	40	3.0:1	act-, conduct-
6	地ち	116	81	1.4:1	terra-, geo-
7	手て	114	97	1.2:1	hand-, manu-
8	事こと	110	27	4.1:1	affair-, event-
9	道みち	109	25	4.4:1	path-, via-
10	目め	109	44	2.5:1	eye-, view-

子こ (child) and 事こと (thing) are extremely left-dominant - they hardly ever appear as the second element.

The Most "Suffix-like" (Right-Dominant)¶

These kanji appear most often as the second element:

Rank	Kanji	Right	Left	Ratio R:L	English Analogy
1	一いち	231	19	12.2:1	-unity, -one
2	大だい	228	57	4.0:1	-large, -big
3	小しょう	149	19	7.8:1	-small, -minor
4	同どう	117	22	5.3:1	-same, -identical
5	本ほん	116	61	1.9:1	-origin, -book
6	自じ	108	4	27:1	-self
7	内ない	107	60	1.8:1	-inside
8	高たか	104	32	3.3:1	-high, -expensive
9	者しゃ	87	1	87:1	-er, -ist
10	性せい	80	26	3.1:1	-ity, -ness

The strongest suffixes are 者しゃ (87 right vs 1 left) and 自じ (108 vs 4): they almost never begin a compound. The classic grammatical suffixes 的てき, 性せい, and 化か behave the same way (see the family breakdown below).

The mirror image is negation. 不ふ and 無む are the strongest prefixes in the database (161 and 153 left-side compounds, with almost none on the right), which is why they sit in the left-dominant list above, not here.

Deep Dive by Kanji Family¶

4.1 Big/Small - 大小¶

Kanji	Meaning	Left	Right	Total	Position preference
大だい	big	57	228	285	Strongly Right
小しょう	small	19	149	168	Strongly Right

大だい is the #1 overall by total compounds. It's extremely productive on the right side:

大だい on the right (like a suffix): - 最大さいだい (maximum - most big) - 拡大かくだい (expansion - spread big) - 巨大きょだい (huge - giant big) - 強大きょうだい (powerful - strong big) - 壮大そうだい (grand - majestic big) - 重大じゅうだい (serious - heavy big) - 絶大ぜつだい (enormous - extreme big)

大だい on the left (like a prefix): - 大学だいがく (university - big study) - 大事だいじ (important - big matter) - 大部分だいぶぶん (most part - big portion) - 大使たいし (ambassador - big envoy)

小しょう on the right: - 最小さいしょう (minimum - most small) - 縮小しゅくしょう (shrink - contract small) - 微小びしょう (tiny - minute small) - 弱小じゃくしょう (weak - weak small)

4.2 Negation - 不無非未¶

Kanji	Meaning	Left	Right	Total	Position
不ふ	not	161	0	161	Exclusively Left
無む	without	153	4	157	Almost exclusively Left
非ひ	not, anti-	38	12	50	Left-dominant (prefix)
未ひつじ	not yet	41	8	49	Left-dominant (prefix)

All four negation kanji are left-side (prefix-like) elements - they attach to the beginning of a compound to negate or modify it:

不ふ + 可能かのう = 不可能ふかのう (impossible)
無む + 料りょう = 無料むりょう (free, without charge)
非ひ + 公開こうかい = 非公開ひこうかい (not public)
未ひつじ + 来らい = 未来みらい (future, not yet come)

不ふ compounds (不ふ in FIRST position): - 不安ふあん (anxiety - not + peaceful) - 不便ふべん (inconvenient - not + convenient) - 不満ふまん (dissatisfaction - not + full) - 不可能ふかのう (impossible - not + possible) - 不正ふせい (injustice - not + correct) - 不十分ふじゅうぶん (insufficient - not + enough) - 不注意ふちゅうい (careless - not + careful) - 不意ふい (unexpected - not + intentional)

無む compounds: - 無料むりょう (free - without + fee) - 無限むげん (infinite - without + limit) - 無意味むいみ (meaningless - without + meaning) - 無関心むかんしん (indifferent - without + interest)

4.3 People - 人者子¶

Kanji	Meaning	Left	Right	Total	Position
人ひと	person	173	96	269	Strongly Left
子こ	child	156	27	183	Extremely Left
者しゃ	person (role)	1	87	88	Strongly Right

者しゃ is the go-to suffix for creating agent nouns ("-er" / "-ist"). Nearly all its compounds have it on the right side: - 医者いしゃ (doctor), 科学者かがくしゃ (scientist), 読者どくしゃ (reader), 記者きしゃ (journalist), 労働者ろうどうしゃ (worker)

The single left-hand compound is likely 者共ものとも (those people / they), a rare usage.

4.4 Abstract Suffixes - 的性化¶

From the first query (specific kanji):

Kanji	Meaning	Left	Right	Total	Position
的てき	-ic, -al	3	34	37	Right (suffix)
性せい	-ity, nature	26	80	106	Right (suffix)
化か	-ization	12	57	69	Right (suffix)

All three are right-dominant - they are classic suffixes: - 的てき: 科学的かがくてき (scientific), 経済的けいざいてき (economic), 具体的ぐたいてき (concrete) - 性せい: 可能性かのうせい (possibility), 安全性あんぜんせい (safety), 重要性じゅうようせい (importance) - 化か: 現代化げんだいか (modernization), 自動化じどうか (automation), 国際化こくさいか (internationalization)

Important nuance - 的てき has two lives: 1. As a suffix meaning "-ic/-al": 科学的かがくてき, 経済的けいざいてき - Right position (the dominant usage) 2. As a noun meaning "target": 目的もくてき (purpose), 的中てきちゅう (hit the mark) - Left position (3 compounds)

4.5 Systems - 制体制成¶

From the first query:

Kanji	Meaning	Left	Right	Total
制せい	system, control	32	20	52
成せい	become, form	39	35	74
体からだ	body, system	28	31	59

制せい (52 total compounds) - moderate but reliable productivity:

制せい on the left (prefix): - 制度せいど (system - system + degree) - 制限せいげん (restriction - system + limit) - 制御せいぎょ (control - system + drive) - 制作せいさく (production - system + make)

制せい on the right (suffix): - 体制たいせい (structure - body + system) - 規制きせい (regulation - rule + system) - 統制とうせい (control - unified + system) - 抑制よくせい (suppression - restrain + system) - 強制きょうせい (compulsion - force + system) - 法制ほうせい (legislation - law + system) - 節制せっせい (moderation - moderate + system)

成せい (74 total compounds) - balanced between left and right:

成せい on the left (prefix): - 成功せいこう (success - become + merit) - 成果せいか (result - become + fruit) - 成長せいちょう (growth - become + long) - 成熟せいじゅく (maturity - become + ripe) - 成立せいりつ (establishment - become + stand)

成せい on the right (suffix): - 完成かんせい (completion - finish + become) - 構成こうせい (composition - construct + become) - 形成けいせい (formation - shape + become) - 養成ようせい (training - nurture + become) - 育成いくせい (fostering - raise + become) - 達成たっせい (achievement - attain + become) - 賛成さんせい (agreement - support + become)

制せい and 成せい together: The common compound 体制たいせい (system + system = structure/system) uses both.

4.6 Location - 上下中内外¶

Kanji	Meaning	Left	Right	Total	Balance
上うえ	up, above	84	101	185	Balanced
下した	down, below	78	99	177	Balanced
中なか	middle, in	80	102	182	Balanced
内ない	inside	60	107	167	Somewhat Right
外そと	outside	64	92	156	Somewhat Right

Location kanji are the most balanced - they appear freely on both sides.

上うえ: 以上いじょう (above), 上昇じょうしょう (rise), 地上ちじょう (ground), 水上すいじょう (on water) 下した: 以下いか (below), 下降かこう (descent), 地下ちか (underground), 状況下じょうきょうか (under circumstances) 中なか: 中国ちゅうごく (China), 集中しゅうちゅう (concentrate), 空中くうちゅう (in the air), 水中すいちゅう (in water) 内ない: 国内こくない (domestic), 市内しない (within city), 内部ないぶ (interior) 外そと: 外国がいこく (foreign), 外部がいぶ (exterior), 以外いがい (except), 海外かいがい (overseas)

The Balanced vs Unbalanced Kanji¶

A key insight from the data: some kanji naturally want to be on one side or the other.

Extremely Unbalanced (L:R ratio > 3:1 or < 1:3)¶

Kanji	L:R Ratio	Natural Position
不ふ	161:0	Exclusively left (prefix)
無む	153:4	Almost exclusively left (prefix)
子こ	156:27	Strongly left
事こと	110:27	Strongly left
物もの	144:39	Strongly left
行こう	119:40	Strongly left
目め	109:44	Strongly left
小しょう	19:149	Strongly right
大だい	57:228	Strongly right

Balanced (L:R ratio between 0.7 and 1.5)¶

Kanji	L:R Ratio	Example compounds both ways
上うえ	84:101	以上いじょう / 上昇じょうしょう
下した	78:99	以下いか / 下降かこう
中なか	80:102	中国ちゅうごく / 集中しゅうちゅう
金きん	85:88	金額きんがく / 資金しきん
出しゅつ	77:91	出版しゅっぱん / 輸出ゆしゅつ
外そと	64:92	外国がいこく / 以外いがい
水みず	113:121	水平すいへい / 海水かいすい

Practical Takeaways¶

1. Learn by Side Preference¶

If a kanji is strongly left-dominant (like 人ひと, 事こと, 行こう), learn it as a prefix-like root - it modifies the next kanji.

If a kanji is strongly right-dominant (like 者しゃ, 的てき, 性せい, 化か), learn it as a suffix-like root - it gets modified by the preceding kanji.

2. The 不 Discovery¶

不ふ has zero right-hand compounds. It only appears in the first position - this confirms 不ふ is a pure prefix. When you see 不ふ in a jukugo, 不ふ is always on the left, negating whatever follows:

不ふ + 可能かのう (possible) = 不可能ふかのう (impossible)
不ふ + 安あん (peace) = 不安ふあん (anxiety, unease)

This aligns with how every textbook explains it - 不ふ = "un-/in-/dis-" as a prefix.

3. Your Specific Kanji: 制 and 成¶

Kanji	Total compounds	Common meaning	Primary position
制せい	52	system, control	Left (32L, 20R) - somewhat left
成せい	74	become, form	Balanced (39L, 35R) - almost 50/50

制せい leans left - it often sets the system: - 制度せいど (system), 制限せいげん (restriction), 制御せいぎょ (control), 制作せいさく (production)

成せい is balanced - it can be the action or the result: - Left: 成功せいこう (success), 成長せいちょう (growth) - "becoming" as action
- Right: 完成かんせい (completion), 構成こうせい (composition) - "become" as result

4. The Database as a Learning Tool¶

You can query the Kanji Database yourself at kanjidatabase.com:

-- Find the most productive kanji as prefixes (left-hand)
SELECT `Kanji`, `Left Kanji Prod.` FROM `KanjiTable` ORDER BY `Left Kanji Prod.` DESC LIMIT 20;

-- Find the most productive kanji as suffixes (right-hand)  
SELECT `Kanji`, `Right Kanji Prod.` FROM `KanjiTable` ORDER BY `Right Kanji Prod.` DESC LIMIT 20;

-- Check a specific kanji
SELECT `Kanji`, `Left Kanji Prod.`, `Right Kanji Prod.` FROM `KanjiTable` WHERE `Kanji` = '制';

Source¶

Database: Tamaoka, K., Makioka, S., Sanders, S. & Verdonschot, R.G. (2017). www.kanjidatabase.com: A new interactive online database. Psychological Research, 81, 696-708.
Original research: Tamaoka, K. & Altmann, G. (2004). Symmetry of Japanese Kanji Lexical Productivity on the Left- and Right-hand Sides. Glottometrics, 7, 68-87.
SQL queries: Executed directly against kanjidatabase.com on 2026-06-03.

Note on numbers: every productivity count on this page comes from the 2017 Kanji Database (11-year newspaper corpus, 2,136 Jōyō kanji). The Catalog organizes these same kanji by meaning without repeating the figures, so each number lives in exactly one place.