Korean makes you learn to count twice. There is a native Korean system (하나, 둘, 셋, 넷…) inherited from Old Korean, and a Sino-Korean system (일, 이, 삼, 사…) borrowed from Chinese, and they are not interchangeable. Each one owns a fixed set of jobs. Native numbers count tangible things, tell the hour, and give your age; Sino numbers handle dates, money, minutes, phone numbers, measurements, and anything from 100 up. The governing question is never "which is easier" but "what am I counting?" — the context picks the system for you.
The part that trips everyone up is that a single utterance often uses both at once. A clock time like 세 시 삼십 분 ("3:30") is native for the hour and Sino for the minutes. This isn't a quirk to memorize sentence by sentence; it's the natural result of each system doing its assigned job.
Native Korean: things, hours, age
Reach for native numbers (하나, 둘, 셋, 넷, 다섯…) when you are:
- counting physical things with a counter (개, 명, 마리, 잔, 권…),
- telling the hour of the clock (with 시), or
- stating age (with 살).
지금 세 시예요.
jigeum se siyeyo
It's three o'clock now.
커피 두 잔 주세요.
keopi du jan juseyo
Two coffees, please.
사과 세 개 주세요.
sagwa se gae juseyo
Three apples, please.
저는 스물다섯 살이에요.
jeoneun seumuldaseot sarieyo
I'm twenty-five years old.
저는 고양이 세 마리를 키워요.
jeoneun goyangi se marireul kiwoyo
I have three cats.
The special pre-counter shapes
Native numbers 1–4 and 20 change form when a counter follows. You never say ×하나 개; the counting form is 한 개. Memorize these five — they are extremely high-frequency:
| Alone | Before a counter | Example |
|---|---|---|
| 하나 (1) | 한 | 한 개, 한 명, 한 시 |
| 둘 (2) | 두 | 두 개, 두 명, 두 시 |
| 셋 (3) | 세 | 세 개, 세 명, 세 시 |
| 넷 (4) | 네 | 네 개, 네 명, 네 시 |
| 스물 (20) | 스무 | 스무 개, 스무 살 |
Sino-Korean: dates, money, minutes, and big numbers
Reach for Sino numbers (일, 이, 삼, 사, 오…) for everything measured, dated, priced, or labeled:
- dates — year, month, day (with 년, 월, 일),
- money (with 원),
- minutes and seconds (with 분, 초),
- phone numbers, addresses, exit numbers, bus numbers — any label or code,
- measurements (킬로미터, 그램…), and
- any number 100 and above.
지금 세 시 삼십 분이에요.
jigeum se si samsip bunieyo
It's three thirty now.
That single clock time shows both systems shaking hands: 세 (native) for the hour, 삼십 (Sino) for the minutes. Say it aloud a few times — it's the pattern you'll use every day.
제 생일은 십이월 오 일이에요.
je saeng-ireun sibiwol o irieyo
My birthday is December 5th.
이거 삼천오백 원이에요.
igeo samcheonobaek wonieyo
This is 3,500 won.
오 번 출구로 나오세요.
o beon chulguro naoseyo
Come out of exit 5.
Notice 오 번 (exit "number 5"): a number used as a label is Sino, even though you could physically point at five exits. The distinction isn't "can I touch it" but "am I counting a quantity or reading a code?" A code is Sino.
The switch at 99
Native numbers only run comfortably up to 99 (아흔아홉). Beyond that there is no everyday native word — you switch to Sino at 100 (백). So even things you'd normally count with native numbers get read in Sino once they climb past ninety-nine. In practice, native numbers dominate small everyday counts, and Sino takes over for anything large.
교실에 학생이 백 명 있어요.
gyosire haksaeng-i baek myeong isseoyo
There are a hundred students in the classroom.
Here 백 (100) is Sino by necessity, even though 명 is a counter that usually rides with native numbers below 100 (한 명, 두 명…). The counter stays; only the number system flips.
Phone numbers: Sino, one digit at a time
Phone numbers are pure Sino, read digit by digit rather than as whole quantities. Zero is spoken 공 (not the other Sino zero 영), and the hyphens between blocks are read as 에 or simply paused over. So 010 is 공일공, not "ten."
제 번호는 공일공에 일이삼사에 오육칠팔이에요.
je beonhoneun gong-ilgong-e irisamsa-e oyukchilparieyo
My number is 010-1234-5678. (read digit by digit)
The same digit-by-digit Sino reading covers room numbers, PINs, and card numbers — anything that's a string of digits rather than a count of things. Reading such a code with native numbers would sound as strange as an English speaker saying "one thousand ten" for the area code 010.
Age has a formal Sino twist
Everyday age is native + 살 (스무 살, 서른 살). But in formal or respectful contexts, age is expressed with the Sino counter 세 — and for an elder's age you use the honorific noun 연세. This is why a form or a doctor's office may ask 나이 with 세 rather than 살. See age with 세 and 연세 for the full picture.
Common Mistakes
1. Mixing systems inside a clock time. The hour is native; the minutes are Sino. Reading the minutes in native is the single most common time error.
❌ 세 시 세 분.
se si se bun
Wrong — minutes are Sino: 삼 분.
✅ 세 시 삼 분.
se si sam bun
Three oh three (3:03).
2. Using native numbers for months. Months are Sino: 일월, 이월, 삼월… February is 이월, never ×둘 월.
❌ 둘 월.
dul wol
Wrong — February is Sino.
✅ 이월.
iwol
February.
3. Using Sino numbers to count objects. Tangible things counted with a counter take native numbers. "Three items" is 세 개, not ×삼 개.
❌ 사과 삼 개.
sagwa sam gae
Wrong — count objects with native numbers.
✅ 사과 세 개.
sagwa se gae
Three apples.
4. Forgetting the pre-counter form. Native 1–4 and 20 reshape before a counter. 하나 개 is wrong; the counting form is 한 개.
❌ 하나 개.
hana gae
Wrong — use the counting form 한.
✅ 한 개.
han gae
One item.
5. Using native numbers for money. Prices are always Sino, and native numbers don't reach that high anyway. 5,000 won is 오천 원, not ×다섯천 원.
❌ 다섯천 원.
daseotcheon won
Wrong — money is Sino, and native has no 천.
✅ 오천 원.
ocheon won
Five thousand won.
Key Takeaways
- Native (하나, 둘, 셋): counting things (with counters), the hour, and age — up to 99.
- Sino (일, 이, 삼): dates, money, minutes, phone numbers, labels, measurements, and everything 100 and up.
- The two co-occur in one phrase: 세 시 삼십 분 = native hour + Sino minutes.
- Native 1–4 and 20 take special pre-counter shapes: 한, 두, 세, 네, 스무.
- Past 99, everything switches to Sino (백, 천, 만…), even things you'd normally count natively.
For each system in full, see native Korean numbers and Sino-Korean numbers; for the pre-counter shapes, native forms before counters; and for telling time, the hour with 시.
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Start learning Korean→Related Topics
- Native Korean Numbers: 하나, 둘, 셋…TOPIK 1 — The home-grown numerals 하나·둘·셋·넷·다섯…열 are Korean's counting system for tangible things — objects, people, animals, age, and clock hours — and they run only from 1 to 99, with no native word for a hundred.
- Sino-Korean Numbers: 일, 이, 삼, 사…TOPIK 1 — The borrowed-from-Chinese number system that Korean uses for dates, money, minutes, and anything measured or abstract — and how it builds every number from ten simple digits by pure place value.
- The Forms That Change: 한, 두, 세, 네, 스무TOPIK 1 — The classic Korean-beginner rule: 하나·둘·셋·넷·스물 drop their ending and become 한·두·세·네·스무 the moment a counter follows — 한 개, 두 명, 세 마리, 네 시, 스무 살, never ×하나 개.
- The Hour Uses Native Numbers: 한 시, 두 시TOPIK 1 — Clock hours take NATIVE numbers with the counter 시 — 한 시, 두 시, 세 시 … 열두 시 — using the determiner forms 한·두·세·네. The question is 몇 시예요? Never Sino ×삼 시 for 3:00. And the clock is the showcase where you switch systems: native hour, Sino minute.