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Having learned Sino-Japanese numbers, simply knowing these numbers is only one part to counting things. To count thing in Japanese, you must combine a number with what is called a "counter."

The Japanese word for counters, 助数詞, can literally be interpreted as "number helpers" because of how they aid numbers in counting things. Hundreds of counters exist, grouping everything that can be counted into finite categories. Of these hundreds of counters, several dozen are used in everyday speech.

Before learning the basic counters in Japanese, it's important to relate counters to corresponding words in English. The words in bold in the sentences below function the same way counters do in Japanese.

i.       When you go to the supermarket, could you buy a gallon of milk?
ii.       How many loaves of bread are left in the cupboard?
iii.       Why did you only give me three slices of ham?
iv.       How many times did you go?
v.       I have four volumes of the same book.

The 15 counters introduced in this lesson are some of the most commonly used counters of Sino-Japanese origin, avoiding those with particularly irregular readings to make the learning process less daunting. That being said, for every counter that is discussed, the goal is to get the gist of how to use the counter. That way, as you learn more nouns, you'll know which counter to use. 

Format Note: Whenever a counter expression has more than one reading, readings will be listed by frequency from most to least common. 

Chart Note: "?" in the charts stands for how to say "how many #."

The currency of Japan is the yen. The presence of /y/ in the English word actually derives from the original pronunciation of the word. In Modern Japanese, though, the word is pronounced as /e.N/, with the "n" notably being ん. When counting yen, the word 円 functions as a counter, and it combines with numbers as follows: 

※When ～円 follows 4, 4 is read as よ rather than よん or シ. However, it is not the case that よん changes to よ. In fact, the opposite is true. よ is the original pronunciation of the native number for 4. It is preserved in phrases like ４円, and you will see よ occur in similar key expressions.

Counter phrases function as adverbial nouns. For instance, in "please give me 500 yen," there won't necessarily be a case particle between "500 yen" and the verb for "to give" because the phrase "500 yen" may directly modify the verb.

1. 五百円（を）ください。
Give me 500 yen. 

Inserting the particle を is not grammatically incorrect, but its presence would cause the 500 yen to be  viewed more as a material object. To demonstrate this sort of nuance further, consider the following. 

2. ５００ドル相当の円をください。

Please give me yen equivalent to 500 dollars. 

Other currency words like ドル (dollars) also function as counters. Notice also how 円 is being used as a standalone noun. Not all counters can be used as standalone nouns, but many can be, and those counters will especially exhibit this dual adverb-noun functionality. 

3. 5円玉を搔き集めました。

I scraped up five-yen coins.

4. きょう、1万円札を拾いました。
Today, I picked up a 10,000-yen bill.

Whenever a counter phrase is used in compound expressions or is followed by the particle の, that is a sign that it is being used as a noun. Conversely, if you don't see any case particles around it, it is being used as an adverb. 

5. 250円のお返しでございます。
Here is (your) 250 yen in change.

The kanji 冊, originally written as 册, is a pictograph of books bound by string. Consequently, it is used as a counter in Japanese to count books, magazines, etc.

※The number 一 (1) undergoes a sound change from イチ to イッ before counters that begin with the consonants /k/, /s/, /t/, and /h/. 

※The number 八 (8) undergoes a sound change from ハチ to ハッ before counters that begin with the consonants /k/, /s/, /t/, and /h/. 

※The number 十 (10) undergoes a sound change from ジュウ to ジュッ or ジッ before counters that begin with the consonants /k/, /s/, /t/, and /h/. ジュッ is the predominant reading, but it is relatively new. In news and other situations were speakers feel the need to more proper, ジッ is preferred. 

6. 私は【本・雑誌・百科事典・ラノベ】が51冊あります。
I have 51 [books/magazines/encyclopedia/light novels].

7. （本を）６冊借りました。
I borrowed six books.

8. もう一冊読みました。
I read one more book.

9. テイラー君は（本を）何冊借りましたか？
How many books did you borrow, Taylor?

The counter 課 stands for "lesson," but it can also mean "division" as in "department." It is often with the prefix 第～ to indicate "Lesson/Department #."  

※The number 百 (100) undergoes a sound change from ヒャク to ヒャッ before counters that begin with the consonants /k/ and /h/. 

10. 『いまび』という教材は５００課から構成されています。
The teaching material "IMABI" is composed of 500 lessons.

11. 1課分が範囲でした。
One lesson's worth was the scope. 

12. 第１課から順に進めることをお勧めします。
We recommend progressing in order from Lesson 1.

13. テキストに従って、ほぼ2週間で1課を終えるように進めたいと考えている。
I like to recommend that you try to complete 1 lesson in about 2 weeks following the text. 

14. 第８課を学習します。
We will study Lesson 8.

15. 営業（第）二課は変更（が）ありません。
There will be no changes to Sales Department No. 2.

Grammar Note: 第 is often omitted. In proper nouns, it is never understood as a quantity of "departments" as it is most proper to refer to departments individually. When 課 is used to mean "lesson" and is not used with 第, it could either still refer to a particular lesson or a quantity of lessons. 

課 & Its Synonyms

A written work may be broken up into chapters (章), units (単元), sections (セクション), or lessons (レッスン・課). These all function as counters, but there is no inherent difference between them in how much volume of content is indicated.

16. この教科書は第何課までありますか。
Up to what lesson is in this textbook?

17. この教科書には何セクションありますか。
How many sections are in this textbook?

18. その教科書にはいくつの単元がありますか。
How many units are in that textbook?

Grammar Note: "How many" is expressed with いくつ whenever a counter is not common enough to be used with the prefix 何～, especially in the spoken language.

The counter ～歩 is used to count steps, whether they be physical steps or metaphorical steps as in progress being made.

※When a Sino-Japanese counter beginning in the consonant /h/ follows a number that ends in /N/ or the prefix 何～, /h/ will either manifest as [b] or [p] with the latter being far more common. In the case of ～歩, all instances of [p] can still be heard as [b] among older generations. 

19. 毎日5千歩くらい歩きます。
I walk about five thousand steps every day.

20. ｛一歩一歩・一歩ずつ｝進んでいきます。
I'm going to push forward one step at a time.

The counter ～枚 is arguably the third most used counter in Japanese after ～つ and ～個 due to the array of things that in count. At its basic understanding, it is primarily used to count flat, thin objects. These objects may vary in shape to a degree, mostly being either circular or squarish but never bulky or cylindrical. 

Things that are perceived as being flat that are counted with ～枚 include: pieces of paper, pictures, paintings, photographs, windows, mats, cutting boards, rugs, CDs, DVDs, cash, towels, handkerchiefs, shirts, mattresses, fillets of fish, etc. 

21. 海外旅行にクレジットカードを何枚持っていけばいい？
How many credit cards is best to have on you when you go traveling overseas?

22. シャツが3枚あります。
There are three shirts.

23. 公園には標識が5枚あります。
There are five signs in the park.

24. 絵を一枚描いてみました。
I tried drawing one picture.

25.１０枚セットのお皿のうち、一枚だけヒビがあります。
In a set of ten plates, only one has cracks in it.

26. 鯖（サバ）を三枚におろしました。
I filleted the mackerel into three pieces. 

27. 今お財布には五百円玉が4枚入っています。
There are four 500-yen coins currently in my wallet.

28. ACMEのCDを２枚買いました。
I bought 2 CDs of ACME.

29. 昼ご飯にホットケーキを8枚食べたせいで、気分が悪いんです。
I don't feel good because of the eight pancakes I ate for lunch.

Counter Note: ～枚 is generally interchangeable with～個 when counting coins, but when size is of importance, the former is preferred for larger coins such as the 500-yen coin and the latter is used for smaller coins. 

Aside from flat objects, ～枚 may also count positions/roles in set phrases. This is so much so that in kabuki theatre, actors may even be counted with it because at one time their faces were painted on billboards. This brought about the phrases 一枚目 (the main actor), 二枚目 (handsome actor (in love scene), and 三枚目 (actor who serves comedic role or as the laughing stock). 

30. あの隊員は、陰謀に一枚噛んでいることが判明した。
It was confirmed that that troop member had been involved in the conspiracy. 

Other minor things that may be counted with ～枚 that are tied to these main meanings include the following:

• Fish (that are flat in shape)
• Sumo ranks below komusubi. 
• (Rice paddy) fields
• Imperial court (singing) performers
• Palanquin bearers
• Servings of gyoza/yakisoba, etc. 
• Large monetary gold/silver plates.

The counter ～匹 is used to count small to medium-sized animals such as dogs, cats, ferrets, monkeys, insects, reptiles, amphibians, robot animals, monsters, people acting like animals, and fish that are notably still alive. 

※[h] → [b] is obligatory when ～匹 appears after a Sino-Japanese numeral ending in /N/ as well as after the prefix 何～.  Hearing [p] instead is heard on occasion, but such pronunciations are not considered standard.  

Orthography Note: In older writing, this counter may also be seen written as ～疋.

29. この家には犬が10匹、猫が5匹います。
There are ten dogs and five cats in this house.

30. 子猫6匹と暮らしています。
I am living with 6 kittens.

31. うちはチビが１匹いるから、高級レストランは難しいな。
I have a little brat at home, so fancy restaurants are pretty tough. 

32. フシギダネを４匹捕まえた。
I caught four Bulbasaur.

33. ケイトさんはフェレットを二匹飼っています。
Kate owns two ferrets. 

～匹 can even count viruses, both biological and virtual ones. However,～個 is the normal counter in these situations. 

34. ウイルスが百匹【の・である】時期は、まず陽性には出ません。
During the time you have 100 copies of the virus, firstly, you won't show up positive.

Large-sized animals are generally counted with ～頭. Think "heads" of cattle to determine as a decent metric for whether an animal should be counted with it. It must be noted that this counter has considerable overlap with ～匹.

～頭 is often preferred over ～匹 in formal, academic settings or situations in which a person doesn't wish to be unnecessarily derisive when counting said animal. If there is some sort of value in said animal, it will most likely be counted with ～頭 regardless of the size of the animal. One exception that catches the attention of native speakers is counting butterflies with ～頭.

35. イルカが3頭います。
There are three dolphins.

36. ヒョウが4頭います。
There are four leopards.

37. パンダが8頭います。
There are eight pandas.

The kanji 足 means "foot," and although it is the ON reading ソク that is used as a counter, this counter is used to count things that you put on your feet: shoes, boots, slippers, socks, geta, skates, etc.

※When ～足 follows a Sino-Japanese number ending in /N/, it becomes voiced as ゾク. This also applies when used with the prefix 何～. Nowadays, fewer people are voicing this counter, but the voiced readings are still considered the most proper. 

43. 靴を1足買いました。
I bought one pair of shoes.

44. サンダルが2足あります。

[There are/I have] two pairs of sandals.

45. 下駄は今も5足あります。
I still have five pairs of geta.

The counter ～台 is used to count mechanical objects of any size and kind. If it is a man-mind appliance, it is counted with it. This includes vehicles, bicycles, pianos, TVs, computers, cellphones, tablets, lawnmowers, etc. 

46. 日本国内には車は何台ありますか。
How many cars in Japan?

47. この2台のPCを繋ぎます。
I’m going to connect these two PCs.

48. 端末を10台発送しました。
I shipped ten devices.

※For any number that ends in 3, 階 may be read がい, which is viewed as the traditional, proper pronunciation. Voicing the counter before /N/ with Sino-Japanese vocabulary used to obligatory, but it is falling out of use.
※As for the number 8 and numbers ending in said digit, it is often read as はち by announcers on planes, trains, buses, elevators, etc., to be heard better. 

49. 花屋は3階にあります。
The florist is on the third floor.

50. マンションの4階に住んでいます。

I live on Floor 4 of an apartment complex.

To refer to "#-story building," the suffix ～建て is added to ～階 to represent how many stories/floors were built in the structure. These structures don't have to be limited to buildings. In fact, you can see it used with buses, ships, etc. 

51. この建物は何階建てですか。
How many floors does this building have?

52. 二階建てのバスからの景色は最高でした。
The scenery from the double-decker bus was the best.

The kanji 歳 means" year" and is associated with annual events. When used as a counter, ～歳 counts "years old" for living things.

※The word はたち stands out as being particularly exceptional. The reason for this is because it is the native phrase for "twenty-years-old" that has survived into the present. A major reason for this is that 20 has traditionally been viewed as the age in which one enters adulthood, although in modern times, this age is gradually being changed to 18 to match with other Western countries. 

Orthography Note: This counter may also alternatively written as 才, which may be confusing given that this Kanji has no meaning associated with "year" or "age" for that matter. Instead, it has the meaning of "talent." The reason was it was chosen to be an abbreviation for 歳 is that its original abbreviation - 戈 without the final stroke - greatly resembles 才. 

53. 18歳の未成年が3人います。
There are three minors aged 18.

54. 80歳のおばさんも参加しました。
An eighty-year old lady also participated.

55a. 何歳ですか。
55b. おいくつですか。
How old are you?

Grammar Note: 55b is the way to say "how old are you?" with native vocabulary, and it is considered politer than 55a. 

Unless personification is involved, the age inanimate objects is not expressed with this counter but with "X年物." As for the age of structures, this is usually expressed with 築X年. 

56. 友達の家に八年物のウイスキーがある。
There is eight-year-old whiskey at my friend's house.

57. 築百年の古民家を買って修復しました。
I bought and reformed a 100-year-old, old-style Japanese house.

※When a Sino-Japanese counter beginning in the consonant /h/ follows a number that ends in /N/ or the prefix 何～, /h/ will either manifest as [b] or [p] with the latter being far more common. In the case of ~杯, only [b] is recognized. 

58. コーヒーを一杯飲みました。
I drank a cup of coffee.

59. イカ１杯の重さを量りました。
I measured the weight of one squid.

60. 地元のカニを２使いました。
I used two local crabs.

61. 大型のタコを３杯も釣りました！

I caught three large octopuses!

62. 普通の茶碗一杯のご飯の量は約150グラムです。
The volume of rice of an average bowlful is approximately 150 grams. 

As an adverb, 一杯 can be used to mean "to the max," "a lot," etc., indicating that something is being done to a full extent. 

63. 精一杯頑張りましょう！
Let's put out our best effort!

The counter ～本 is most known for counting long, thin items such as pencils, strings, roads, rivers, flutes, film,  etc., but it can count so much more. Other things it counts includes, movies, plays, phone calls, home runs, projects, software products, sports plays, etc.

※When a Sino-Japanese counter beginning in the consonant /h/ follows a number that ends in /N/ or the prefix 何～, /h/ will either manifest as [b] or [p] with the latter being far more common. In the case of ~本, only [b] is recognized. 

64. 鉛筆を3本取ってください。
Please take three pencils.

65. 道一本隔てた寺に参拝しました。
I visited a temple a road away.

66. アニメを10本見ました。
I watched ten anime.

67. 彼は指を5本折った。
He broke five fingers.

Whenever ～個 is being used generically, other possible counters will be shown in tandem. Note that any counter shown that has not been formally introduced may be left for future study. 

68. 積み木は何個ありますか。
How many building blocks are there?

69. 時計は何個ありますか。
How many watches are there/do you have?

Counter Note: For arm watches (腕時計), the counters ～個 and ～本 can be used. For alarm clocks (目覚時計), the counter ～個 is used. For wall clocks (柱時計) or those that hang on the wall (掛け時計), ～個 and ～台 can be used.

70. 四角が10個あります。
There are ten squares.

71. ピアスの穴は何個ありますか。
How many pierces do you have?

72. 夢は100個あります。
I have a hundred dreams.

73. 整数は全部で何個ありますか。
How many integers are there in total?

75. 今朝、卵を｛3個・3つ｝食べました。
I ate three eggs this morning.

76. リンゴを｛1個・ひと玉｝買いました。
I bought one apple.

77. 白い玉が2個あります。

There are two white balls/beads.

78. 荷物は何個ですか。
How many parcels/bags do you have?

79. 新しい製品が｛1万個・1万品｝あります。
There are ten thousand new products.　

80. 牛には胃いが｛4個・4つ｝もあります。
A cow has four stomachs.

81. 人間には細胞が｛何個・いくつ｝ありますか。
How many cells does a human have?