In English you say "three books." In Korean you say the equivalent of "books three [book-counter]."
Counter words (의존 명사) appear after a number and classify what you're counting. Every language has some of this. English says "two pieces of bread" not "two breads." Korean just uses counters far more systematically. The good news: you need about 10 counters for 80% of daily life.
How counters work
Structure: Noun + Native Korean number + Counter
사과 두 개 : two apples (apple + two + generic counter)
책 세 권 : three books (book + three + bound-volume counter)
Note: the noun usually comes before the number + counter in natural speech.
The 10 essential counters
| Counter | Used for | Example |
|---|---|---|
| 개 (gae) | General objects | 사과 한 개: one apple |
| 명 (myeong) | People (neutral) | 학생 두 명: two students |
| 분 (bun) | People (respectful) | 손님 세 분: three guests |
| 권 (gwon) | Books, notebooks | 책 네 권: four books |
| 장 (jang) | Flat things (paper, tickets) | 티켓 두 장: two tickets |
| 병 (byeong) | Bottles | 물 한 병: one bottle of water |
| 잔 (jan) | Cups, glasses | 커피 한 잔: one cup of coffee |
| 번 (beon) | Times, occurrences | 두 번: two times |
| 살 (sal) | Age | 스물다섯 살. 25 years old |
| 마리 (mari) | Animals | 고양이 두 마리: two cats |
The modified number forms
When native Korean numbers come before a counter, 하나→한, 둘→두, 셋→세, 넷→네, 스물→스무.
한 개 (one thing) ✓ NOT 하나 개 ✗
개 is your best friend
When in doubt, use 개: It works for most physical objects and Koreans will understand even if a more specific counter exists. Overusing 개 is a classic learner habit. But it's far better than using the wrong counter.
사과 한 개 ✓ (one apple: 개 works) 사과 한 마리 ✗ (마리 is for animals only)
Special case: people
Use 명 for most people. Switch to 분 when showing respect (customers, elderly, people you don't know well).
어른 두 분이세요? Are there two adults? (restaurant, polite) 친구 세 명 왔어요. Three friends came. (casual)
Practice sentences
커피 두 잔 주세요. Two coffees, please. 책 한 권 빌려도 돼요? Can I borrow one book? 저는 스물셋 살이에요. I'm 23 years old. 강아지 세 마리 있어요. I have three dogs.
The Sino-Korean shortcut
In very casual or fast speech, some Koreans use Sino-Korean numbers with 개 for amounts: 육 개, 칠 개: This is technically non-standard but you'll hear it, especially in markets.
Standard: 여섯 개 (native + 개) ← use this Casual/market: 육 개 (Sino + 개) ← you'll hear this
Counters take time to feel natural. The best approach is to learn new vocabulary with its counter: don't learn 책 (book) alone, learn 책 한 권 as a unit. A structured Korean course presents vocabulary in exactly this pattern from the start.