〜匹: Small Animals | Japanese Grammar

匹（ひき）is the counter for small animals — cats, dogs, fish, mice, insects, frogs, and just about any creature you could pick up or hold. It matters early because animals are everywhere in everyday talk (pets, bugs, the fish at dinner), and it matters phonologically because 匹 begins with h, which means it runs the same three-way sound change as 〜本: ひき / びき / ぴき. The twist that catches English speakers is that "animal" in Japanese is not one category — it splits by size and type across three counters (匹, 頭, and 羽), and 匹 owns the small end.

What 匹 counts

The working definition is an animal small enough to imagine holding, carrying, or scooping up:

Pets: 猫（ねこ, cat）, 犬（いぬ, dog — most dogs）, ハムスター, ウサギ (informally — but see below)
Water creatures: 魚（さかな, fish）, 金魚（きんぎょ, goldfish）, カエル (frog), エビ (shrimp)
Small crawling/flying creatures: 虫（むし, insect）, 蚊（か, mosquito）, アリ (ant), 蝶（ちょう, butterfly）

猫が三匹、庭で寝ている。

neko ga san-biki, niwa de nete iru

Three cats are sleeping in the garden.

金魚を二匹飼っています。

kingyo o ni-hiki katte imasu

I keep two goldfish.

さっき蚊を一匹たたいた。

sakki ka o ippiki tataita

I just swatted a mosquito.

The sound-change table

匹 is h-initial, so it behaves exactly like 本 and 百: gemination hardens h to p after 1/6/8/10, and voicing softens h to b after 3/何. If you have drilled 本, this table will feel familiar — that's the payoff of a single system.

Number	Reading	What happened
一匹	いっぴき (ippiki)	gemination, h → p
二匹	にひき (ni-hiki)	— quiet
三匹	さんびき (sanbiki)	voicing after ん, h → b
四匹	よんひき (yon-hiki)	— quiet
五匹	ごひき (go-hiki)	— quiet
六匹	ろっぴき (roppiki)	gemination, h → p
七匹	ななひき (nana-hiki)	— quiet
八匹	はっぴき (happiki)	gemination, h → p
九匹	きゅうひき (kyū-hiki)	— quiet
十匹	じゅっぴき (juppiki)	gemination (じっぴき jippiki is older)
何匹	なんびき (nanbiki)	voicing after ん, h → b

💡

Set 匹 next to 本 and the parallel is exact: いっぽん／いっぴき (p), さんぼん／さんびき (b), ろっぽん／ろっぴき (p). Same numbers geminate, same numbers voice. This is why the counter system is worth learning as one rule, not as dozens of separate lists — see Counter Sound Changes.

犬を六匹も飼うなんてすごいね。

inu o roppiki mo kau nante sugoi ne

Keeping six dogs — that's impressive.

川で魚が何匹も跳ねている。

kawa de sakana ga nan-biki mo hanete iru

Lots of fish are jumping in the river.

アリが八匹、列を作って歩いている。

ari ga happiki, retsu o tsukutte aruite iru

Eight ants are walking in a line.

うちには犬が一匹と猫が二匹います。

uchi ni wa inu ga ippiki to neko ga ni-hiki imasu

We have one dog and two cats.

"Animal" is not one category: 匹 vs 頭 vs 羽

This is the conceptual heart of the page, and the thing English does not prepare you for. In English, a horse, a hamster, and a pigeon are all just "animals" you count with numbers. Japanese sorts them:

匹 — small animals (the default for pets and anything hand-holdable)
頭（とう） — large animals: cattle, horses, elephants, and often zoo/farm beasts
羽（わ） — birds, and by tradition rabbits

So how many creatures you have is not enough information — you also need to know what kind and how big before you can pick the counter. A cat is 匹; a cow is 頭; a sparrow is 羽.

Where's the line between 匹 and 頭? It's cultural, not metric — there's no centimetre cutoff. The reliable guidance: if you can comfortably pick the animal up, it's 匹. Cattle, horses, elephants, giraffes are unambiguously 頭. The genuinely fuzzy zone is large dogs and big cats: a Shiba is 一匹, but a Great Dane or a police dog is often 一頭, and a lion at a zoo is 頭. When you're unsure with a pet-sized animal, 匹 is the safe choice — no one will blink at 大きい犬が一匹.

大きい犬でも、ペットなら普通は一匹と数えるよ。

ōkii inu demo, petto nara futsū wa ippiki to kazoeru yo

Even a big dog, if it's a pet, is usually counted with 匹.

鳥は一匹じゃなくて、一羽と数えるんだよ。

tori wa ippiki ja nakute, ichi-wa to kazoeru n da yo

You count a bird with 羽, not 匹.

💡

Practical rule for beginners: default to 匹 for anything pet-sized or smaller, use 頭 only for clearly large livestock/zoo animals, and remember birds (and rabbits) take 羽. Getting the size call slightly "wrong" on a big dog is a mild, forgivable choice, not a grammar error — even native speakers vary.

A 匹 idiom: the lone wolf

匹 shows up in the set phrase 一匹狼（いっぴきおおかみ, ippiki-ōkami) — literally "a one-hiki wolf," used exactly like English "lone wolf" for someone who operates alone and answers to no group. It's a handy way to lock in the ippiki reading.

彼はチームより一匹狼タイプだね。

kare wa chīmu yori ippiki-ōkami taipu da ne

He's more of a lone-wolf type than a team player.

Common mistakes

❌ 三匹を「さんひき」と読む

Incorrect — h voices to b after ん: さんびき sanbiki.

✅ 三匹＝さんびき

sanbiki

three (small animals)

❌ 一匹を「いちひき」と読む

Incorrect — 一 geminates and hardens: いっぴき ippiki.

✅ 一匹＝いっぴき

ippiki

one (small animal)

❌ 六匹を「ろくひき」と読む

Incorrect — 六 geminates: ろっぴき roppiki.

✅ 六匹＝ろっぴき

roppiki

six (small animals)

❌ 牛を三匹数える

Incorrect — cattle are large animals; they take 頭 (三頭), not 匹.

✅ 牛を三頭数える

ushi o san-tō kazoeru

counting three cows

❌ 鳥を二匹見た

Incorrect — birds take 羽 (二羽), not 匹.

✅ 鳥を二羽見た

tori o ni-wa mita

I saw two birds.

The two lessons live at different levels. The reading errors (さんひき, いちひき, ろくひき) come from ignoring 匹's h-based sound change — the same one you already know from 本. The counter-choice errors (牛→頭, 鳥→羽) come from treating "animal" as one English-style category when Japanese splits it by size and type. Master both and you've got the whole animal-counting picture; the Which Counter Do I Use? page consolidates the split.

Key takeaways

匹（ひき）counts small animals: cats, most dogs, fish, insects — anything hand-holdable.
It runs the h-counter sound change: いっぴき, さんびき, ろっぴき, はっぴき, じゅっぴき, なんびき — identical in pattern to 本.
"Animal" fractures into 匹 (small) / 頭 (large) / 羽 (birds & rabbits); the 匹–頭 line is cultural, and 匹 is the safe default for pets.
The fuzzy zone is big dogs and big cats, which can go either way; nobody minds 匹 there.

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