Two number systems — which one when?
Korean uses two complete sets of numbers. That is why “three” is 삼 in 삼 층 (3rd floor) but 세 in 세 시 (3 o'clock). The rule of thumb: native numbers count (how many, how old, which hour), Sino numbers label and measure (money, dates, minutes, phone numbers, floors) and take over completely from 100.
Native Native Korean 하나 둘 셋
- Age — 스물한 살 (21 years old)
- Hours on the clock — 세 시 (3 o'clock)
- Counting things & people — 커피 두 잔, 친구 세 명
- How many times — 한 번 (once)
- How many hours — 두 시간 (2 hours)
Sino Sino-Korean 일 이 삼
- Money — 만 오천 원 (₩15,000)
- Minutes & seconds — 삼십 분 (30 min)
- Dates — 시월 십 일 (Oct 10)
- Phone numbers — 공일공… (010…)
- Floors, rooms, buses, lines — 삼 층, 이 호선
- Math, measurements, 100+ — 백 명, 오 킬로
| # | Sino-Korean | Native Korean | Before a counter |
|---|---|---|---|
| 1 | 일 | 하나 | 한 개 |
| 2 | 이 | 둘 | 두 개 |
| 3 | 삼 | 셋 | 세 개 |
| 4 | 사 | 넷 | 네 개 |
| 5 | 오 | 다섯 | 다섯 개 |
| 6 | 육 | 여섯 | 여섯 개 |
| 7 | 칠 | 일곱 | 일곱 개 |
| 8 | 팔 | 여덟 | 여덟 개 |
| 9 | 구 | 아홉 | 아홉 개 |
| 10 | 십 | 열 | 열 개 |
| 20 | 이십 | 스물 | 스무 개 |
Five rules that fix most mistakes
- Hour native, minutes Sino: 두 시 십오 분 (2:15), never 이 시.
- Shorten before counters: 한 개, 두 명, 세 잔, 네 살, 스무 살 — not 하나 개.
- 10,000 is one word: 만. ₩15,000 = 만 오천 원; ₩150,000 = 십오만 원. Never 일만 in speech.
- June and October lose a sound: 유월, 시월 — not 육월, 십월.
- Phone numbers digit by digit, 0 = 공: 010 = 공일공.
Go deeper: Sino-Korean numbers 1–100 and big numbers (만, 억) · native Korean numbers 1–99 · 37 counter words with the right system · telling time in Korean · prices and Korean won.
Questions
What is the difference between Sino-Korean and native Korean numbers?
Korean has two sets of numbers. Sino-Korean numbers (일, 이, 삼…) come from Chinese characters and are used for money, dates, minutes, phone numbers, floors and anything above 99. Native Korean numbers (하나, 둘, 셋…) are used for age, the hour on a clock, and counting things or people with a counter word. Native numbers only go up to 99.
Why is it 한 개 and not 하나 개?
Before a counter word, five native numbers get shorter: 하나 → 한, 둘 → 두, 셋 → 세, 넷 → 네 and 스물 (20) → 스무. The same happens inside bigger numbers: 21 = 스물하나, but 21 years old = 스물한 살.
How do you say the time in Korean?
Say the hour with a native number plus 시 and the minutes with a Sino number plus 분: 3:30 = 세 시 삼십 분, or 세 시 반 (half past three). For AM and PM put 오전 or 오후 in front.
How do Koreans say 10,000?
10,000 is one word, 만 (man) — Korean counts big numbers in groups of four digits. 15,000 = 만 오천, 100,000 = 십만 (ten 만), 1,000,000 = 백만, and 100,000,000 = 일억. Note that 10,000 is just 만, never 일만.
Why does 16 sound like 심뉵 (simnyuk)?
Sound rules change some numbers when you say them: in 십육 an ㄴ sound is added before 육 and the ㅂ becomes ㅁ, so it sounds like [심뉵]. 십일 (11) sounds like [시빌], 백만 like [뱅만]. The converter shows the pronounced form in brackets.
Can I hear the numbers?
Yes — press ▶ next to any reading. It uses the Korean voice built into your phone or computer. If you do not see the ▶ buttons, add a Korean voice in your device's text-to-speech settings.