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匹 / 頭 / 羽 Counters: Counting Animals in Japanese

Japanese mainly uses three counters for animals, split by size: 匹 (ひき, hiki) for small animals, 頭 (とう, tou) for large ones, and 羽 (わ, wa) for birds and, by tradition, rabbits.12 Picking the right one is more a judgment call about size than a fixed rule. That is why these three are worth learning together.

Overview: three counters, one size decision​

A 助数詞 (josūshi), or numeral classifier, sorts nouns by perceived shape or kind.2 Animals are sorted mainly by size. A small set of creatures, namely birds and rabbits, sits outside the size system entirely.

These three counters carve up the animal world, but they do not count people. Humans and human referents take the people counters 人 and 名, never 匹, 頭, or 羽.1

What the three counters cover​

The split is mostly by size, with 羽 as the exception that overrides size:

  • 匹 (ひき) counts small animals: animals roughly human-size or smaller, including cats, dogs, fish, frogs, mice, reptiles, amphibians, and insects.12
  • 頭 (とう) counts large animals: cattle, horses, elephants, whales, dolphins, and the like.13
  • 羽 (わ) counts birds, because the character 羽 means "feather/wing," and, by tradition, rabbits.12

The 匹/頭 division is by perceived size, while 羽 overrides size for birds and rabbits. In practice, 匹 is often used for animals of any size, while many speakers reserve 頭 for larger ones.1

Why so many counters​

A 助数詞 categorizes nouns by perceived shape or kind. Animals are sorted by size much as inanimate objects split between the long-thin counter 本 and the flat-thin counter 枚.2 The parallel is structural, so this article does not re-teach those object counters.

匹 belongs to the same h-row (ハ行) sound-change family as 本, so it geminates and voices in exactly the same places. The systematic phonological reason behind those sound changes is a separate topic. Here, only the surface forms are presented.

匹 (hiki): small animals​

What 匹 counts​

匹 counts small animals: cats, dogs, fish, frogs, and mice, along with reptiles, amphibians, and insects.1 It is the default counter to use when you are unsure which counter a small creature takes.1

By extension, 匹 also counts 鬼 (oni, demons or ogres), which is covered below under register.1

Where the reading ひき may come from

Wiktionary records the reading ひき as associated with 引(ひ)き, "pulling," from the image of leading a tethered animal by a leash.4 Treat this as a dictionary-noted association rather than settled fact.

The readings: 一匹 いっぴき, 三匹 さんびき, 六匹 ろっぴき​

匹 is an h-row (ハ行) counter. It shows the same gemination and voicing pattern as 本.142

NumberKanjiReadingRomaji
1一匹いっぴきippiki
2二匹にひきnihiki
3三匹さんびきsanbiki
4四匹よんひきyonhiki
5五匹ごひきgohiki
6六匹ろっぴきroppiki
7七匹ななひきnanahiki
8八匹はっぴきhappiki
9九匹きゅうひきkyūhiki
10十匹じゅっぴき / じっぴきjuppiki / jippiki
?何匹なんびきnanbiki

The forms to watch are いっぴき (1), さんびき (3), ろっぴき (6), はっぴき (8), じゅっぴき/じっぴき (10), and なんびき (how many). These mirror いっぽん, さんぼん, ろっぽん, じゅっぽん, and なんぼん in 本.14

For 十匹, じっぴき is the traditional prescriptive reading, while じゅっぴき is now dominant in everyday speech. The same じっ～/じゅっ～ split recurs across every h-row counter.5

Here are the irregular forms in natural sentences. Notice さんびき (voiced) and いっぴき (geminated and voiced to p):

猫ねこが三匹さんびきいます。6
"There are three cats."

犬いぬが一匹いっぴき欲ほしい。7
"I want a dog."

The counter attaches the same way whether it comes after the verb or appears inside a の phrase modifying the noun:

彼かれは魚さかなを３匹びき釣つった。8
"He caught three fish."

２匹ひきの犬いぬは眠ねむっている。9
"Both dogs are asleep."

頭 (tou): large animals​

What 頭 counts​

頭 counts large animals you cannot pick up: cattle, horses, lions, tigers, elephants, whales, and dolphins.13 It is also the standard counter in zoo and livestock contexts.

頭 is a documented Meiji-era calque of English "head"

頭 became the general large-animal counter in the Meiji era (1868–1912) as a translation of the English "head," as in "head of cattle." The editor of the 『三省堂国語辞典』 states this directly: "『頭』became generalized in the Meiji era, through the translation of English 'head.'"3 This is documented history, not folk etymology.

Readings and 何頭​

頭 is read regularly as とう, with gemination only at 1, 8, and 10.3

NumberKanjiReadingRomaji
1一頭いっとうittō
2二頭にとうnitō
3三頭さんとうsantō
4四頭よんとうyontō
5五頭ごとうgotō
6六頭ろくとうrokutō
7七頭ななとうnanatō
8八頭はっとうhattō
9九頭きゅうとうkyūtō
10十頭じゅっとう / じっとうjuttō / jittō
?何頭なんとうnantō

There is no voicing or p-/b-mutation here. とう never becomes どう or ぽう. The only changes are the standard small-っ geminations at 1, 8, and 10: いっとう, はっとう, and じゅっとう/じっとう.

Some learner materials list 八頭 as はちとう, but はっとう is the standard counting form. Compared with 匹, 頭 has none of the irregular surface forms. That is the contrast worth noticing.

These sentences show regular とう, including the geminated forms いっとう and じゅっとう:

動物園どうぶつえんから一頭いっとうのトラが脱走だっそうした。10
"A tiger has escaped from the zoo."

牛舎ぎゅうしゃには３頭とうの牛うしがいます。11
"There are three cows in the barn."

The 何頭 question form reads simply as なんとう, with no mutation:

うちには十頭じゅっとうの牛うしがいる。12
"We have ten head of cattle."

何頭なんとうの牛うしを飼かってるんですか？13
"How many cows do you keep?"

羽 (wa): birds and rabbits​

What 羽 counts​

羽 counts birds, including flightless ones such as penguins and ostriches, because 羽 itself means "feather/wing."12 It also counts rabbits by tradition, though everyday speech increasingly uses 匹 for them.1

羽 is read overwhelmingly as わ in modern Japanese. Historically, it was an h-row counter (originally は, ha). The older p-/b-mutated forms survive unevenly, mostly at 3, 6, 8, 10 and in fixed expressions such as 三羽烏 (sanba-garasu).514 The わ forms below are the safe defaults to learn; the mutated variants in parentheses are secondary.

NumberKanjiReading(s)Romaji
1一羽いちわichiwa
2二羽にわniwa
3三羽さんわ (also さんば)sanwa (also sanba)
4四羽よんわyonwa
5五羽ごわgowa
6六羽ろくわ (also ろっぱ)rokuwa (also roppa)
7七羽ななわnanawa
8八羽はちわ (also はっぱ)hachiwa (also happa)
9九羽きゅうわkyūwa
10十羽じゅうわ (also じっぱ / 口語 じゅっぱ)jūwa (also jippa / colloq. juppa)
?何羽なんわ (also なんば)nanwa (also nanba)

The mutated readings are well attested at 3 (さんば), 6 (ろっぱ), 8 (はっぱ), 10 (じっぱ), and 何 (なんば). The most stable forms are 二羽 にわ, 五羽 ごわ, and 九羽 きゅうわ, which take no mutation at all.

Some 羽 variants are minor and not fully verified

Counting references sometimes list further mutated forms, such as いっぱ for 一羽, よんば for 四羽, and しちわ for 七羽. These appear in listings and Q&A but are not uniformly given in the highest-tier dictionaries. Lead with the わ forms and treat these as minor variants rather than co-equal readings.514

For 十羽, 飯田朝子's 『数え方の辞典』 treats じっぱ, or じゅうわ, as standard. It also notes that reading it じゅっぱ in daily life "cannot be called incorrect Japanese."5 In the same mutation family, 1,000 birds is conventionally せんば or せんわ, and 100 is ひゃっぱ or ひゃくわ.5

These examples use 一羽, read いちわ for a single bird:

1羽わの鳥とりが空そらを飛とんでいた。15
"A bird was flying in the sky."

鷲わしが一羽いちわ空そら高たかく飛とんでいた。16
"An eagle was soaring high up in the air."

屋根やねの上うえに鳥とりが一羽いちわ見みえます。17
"I see a bird on the roof."

Why rabbits are counted like birds​

The most commonly cited explanation is that, during periods when people avoided eating four-legged-animal meat for Buddhist reasons, rabbits were treated as "birds" so their meat could be eaten. They then came to be counted with 羽.18 This popular account is broadly framed around pre-modern Buddhist food practice, with the Edo period the usual reference point.

That account is folk etymology, not a documented single cause. The benricho counter reference lists nine distinct proposed origins. They include long ears resembling wings, skeletal resemblance to birds, the two-legged hopping stance, the 「鵜(う)+鷺(さぎ)→うさぎ」 word-play etymology, capture by net as birds are, meat resembling fowl, and a derivation from 一把 (いちわ, a "bundle" of two rabbits tied by the ears).18 No source identifies any one of these as proven.

The oldest cited attestation of the bird-treatment idea is 南方熊楠's 『十二支考』, serialized between 1914 and 1923. It records that rabbits "were not counted 一疋・二疋 but called 一羽・二羽," treated as birds, offered to gods who shun beast-meat, and eaten in the home without taboo.19 Minakata reports the custom but does not settle its origin.

The Buddhist-meat story is one folk theory, not proven history

It is fine to mention the meat-prohibition account, but present it as the most commonly cited of several competing folk explanations rather than as established fact. Multiple origins coexist in the sources, and none has been documented as the single cause.1819

The 匹 / 頭 boundary: judgment, not a hard rule​

How big is "large"?​

The rule of thumb is simple: if you can pick the animal up, use 匹; if you cannot, use 頭.1 The boundary is a judgment call, not a fixed rule.

The fuzzy middle (large dogs, sheep, goats, seals) can take either counter, and speakers genuinely disagree about where the line falls.1

Register also colours the choice. 頭 sounds more formal, zoological, or agricultural, while 匹 is everyday. Defaulting to 匹 is safe when unsure because 匹 is, in practice, used for animals of any size.1

When 羽 overrides size​

Birds take 羽 regardless of size, from a sparrow to an ostrich, because the counter marks "feathered/winged" rather than size.12

Rabbits sit on the 羽-vs-匹 fault line. 羽 is the traditional counter, and 匹 is increasingly common in casual modern speech.118

Good to know​

"When in doubt, 匹" is a safe default​

For any small or medium creature whose counter you do not know, 匹 will be understood. 頭 and 羽 are the marked choices that you reach for deliberately. For the full set of counters beyond animals, see the category reference.1

匹 stretches beyond animals in slang​

匹 also counts 鬼 and monsters such as demons and ogres. It is also used jokingly or derogatorily for unruly people. This usage is informal and is part of 匹's documented scope.1

頭 signals a formal or counting-livestock register​

頭 is heard in news, agriculture, and zoo contexts. Choosing 頭 for a household pet dog can sound clinical rather than affectionate. 匹 is the everyday choice for pets.13

Mnemonics for the irregular forms​

匹's irregular forms map one-to-one onto 本's: いっぴき matches いっぽん, ろっぴき matches ろっぽん, じゅっぴき matches じゅっぽん, and なんびき matches なんぼん.14 If you already know the 本 pattern, you effectively already know 匹. Both are h-row counters with the same "small number plus h-row equals a p-sound" feel. The full systematic explanation belongs to a dedicated sound-changes topic.

See also​

References​

Footnotes​

  1. Wikipedia contributors. "Japanese counter word." Wikipedia. https://en.wikipedia.org/wiki/Japanese_counter_word ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14 ↩15 ↩16 ↩17 ↩18 ↩19 ↩20 ↩21 ↩22 ↩23

  2. ウィキペディア「助数詞」. https://ja.wikipedia.org/wiki/助数詞 ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  3. 飯間浩明（『三省堂国語辞典』編集委員）, interviewed in 神戸新聞「頭、羽…『動物の数え方は死んだ後に残る部位で決まる説』は本当か？ 国語辞典の編集委員に聞いた」. https://www.kobe-np.co.jp/rentoku/omoshiro/202204/0015250384.shtml ↩ ↩2 ↩3 ↩4 ↩5

  4. Wiktionary contributors. "匹." Wiktionary. https://en.wiktionary.org/wiki/匹 ↩ ↩2 ↩3 ↩4

  5. 国立国語研究所協力／飯田朝子. 『数え方の辞典』. 小学館, 2004. (Standard Japanese reference dictionary of counters/josūshi.) Cited here via the JapanKnowledge column drawing directly on it: ジャパンナレッジ「目からウロコ！ 数え方のナゾ」第13回「『10羽』は『じっぱ』が正しい？」 https://japanknowledge.com/articles/kze/column_kaz_13.html ↩ ↩2 ↩3 ↩4 ↩5

  6. Tatoeba Project, sentence #11885829: 「猫が三匹います。」 https://tatoeba.org/en/sentences/show/11885829 ↩

  7. Tatoeba Project, sentence #3552049: 「犬が一匹欲しい。」 https://tatoeba.org/en/sentences/show/3552049 ↩

  8. Tatoeba Project, sentence #108413: 「彼は魚を３匹釣った。」 https://tatoeba.org/en/sentences/show/108413 ↩

  9. Tatoeba Project, sentence #235398: 「２匹の犬は眠っている。」 https://tatoeba.org/en/sentences/show/235398 ↩

  10. Tatoeba Project, sentence #123738: 「動物園から一頭のトラが脱走した。」 https://tatoeba.org/en/sentences/show/123738 ↩

  11. Tatoeba Project, sentence #11195077: 「牛舎には３頭の牛がいます。」 https://tatoeba.org/en/sentences/show/11195077 ↩

  12. Tatoeba Project, sentence #228246: 「うちには十頭の牛がいる。」 https://tatoeba.org/en/sentences/show/228246 ↩

  13. Tatoeba Project, sentence #12146471: 「何頭の牛を飼ってるんですか？」 https://tatoeba.org/en/sentences/show/12146471 ↩

  14. 音訳の部屋「数詞・助数詞の読み方 まやらわ行」. https://hiramatu-hifuka.com/onyak/onyak2/josu-mw.html ↩ ↩2

  15. Tatoeba Project, sentence #235818: 「１羽の鳥が空を飛んでいた。」 https://tatoeba.org/en/sentences/show/235818 ↩

  16. Tatoeba Project, sentence #77128: 「鷲が一羽空高く飛んでいた。」 https://tatoeba.org/en/sentences/show/77128 ↩

  17. Tatoeba Project, sentence #1125958: 「屋根の上に鳥が一羽見えます。」 https://tatoeba.org/en/sentences/show/1125958 ↩

  18. みんなの知識 ちょっと便利帳「ものの数え方・助数詞／兎は、なぜ『一羽』？ 2.兎を『羽』と数える由来は？」. https://www.benricho.org/kazu/column_usagi-2yurai.html ↩ ↩2 ↩3 ↩4

  19. 南方熊楠『十二支考』(「兎に関する民俗と伝説」). Serialized in 『太陽』, 1914–1923. Quoted in source 18. ↩ ↩2