Numbers are where many Korean beginners hit their first real wall — because Korean has two complete number systems, and you have to know when to use each one. It sounds intimidating, but the rules are learnable and consistent. Once you've got them, days, months, dates, time, and prices all fall into place. This guide lays out both systems, the usage rules, and the calendar vocabulary, with romanization throughout.
The two number systems
Korean has native Korean numbers (used for counting) and Sino-Korean numbers (borrowed from Chinese, used for math, money, and dates). Here they are side by side from 1 to 10:
- 하나 / 일hana / il
1 (native / Sino-Korean)
- 둘 / 이dul / i
2
- 셋 / 삼set / sam
3
- 넷 / 사net / sa
4
- 다섯 / 오daseot / o
5
- 여섯 / 육yeoseot / yuk
6
- 일곱 / 칠ilgop / chil
7
- 여덟 / 팔yeodeol / pal
8
- 아홉 / 구ahop / gu
9
- 열 / 십yeol / sip
10
Native numbers traditionally stop being used around 99 — for hundreds and above, Korean switches entirely to Sino-Korean (백 baek = 100, 천 cheon = 1,000, 만 man = 10,000).
When to use which
- Native Korean (하나, 둘, 셋…): counting objects, people, and animals; your age; and the hour when telling time.
- Sino-Korean (일, 이, 삼…): money/prices, dates (year/month/day), minutes and seconds, phone numbers, addresses, and any number 100 or above.
One quirk to memorize: several native numbers shorten before a counter word. 하나→한, 둘→두, 셋→세, 넷→네, and 스물(20)→스무. So 'one person' is 한 명 (han myeong), not 하나 명.
- 사과 세 개sagwa se gae
three apples
Native number (셋→세) + counter 개 (gae) for objects.
- 스무 살seumu sal
20 years old
Native number (스물→스무) + age counter 살 (sal).
- 오천 원ocheon won
5,000 won
Sino-Korean for money: 오 (5) + 천 (1,000) + 원 (won).
Days of the week
Each day ends in 요일 (yoil, 'day of the week'). The first syllable is an element/planet name — a nice pattern once you see it.
- 월요일woryoil
Monday
- 화요일hwayoil
Tuesday
- 수요일suyoil
Wednesday
- 목요일mogyoil
Thursday
- 금요일geumyoil
Friday
- 토요일toyoil
Saturday
- 일요일iryoil
Sunday
Months
Months are wonderfully simple: Sino-Korean number + 월 (wol, 'month'). January is 일월 (1월), February 이월 (2월), and so on. Just watch two irregulars: June is 유월 (not 육월) and October is 시월 (not 십월) — the consonant drops for easier pronunciation.
- 일월irwol
January (1월)
- 유월yuwol
June (6월) — irregular!
- 시월siwol
October (10월) — irregular!
- 십이월sibiwol
December (12월)
Telling the date
Korean dates go from biggest unit to smallest: year, month, day. All three use Sino-Korean numbers, with 년 (nyeon) for year, 월 (wol) for month, and 일 (il) for day.
- 2026년 5월 30일icheon-isibyuk-nyeon owol samsibil
May 30, 2026
Year → month → day, all Sino-Korean. Read 30 as 삼십 (samsip).
- 오늘은 무슨 요일이에요?oneureun museun yoirieyo?
What day of the week is it today?
Telling time (the system mix)
Time is the classic example of using both systems in one sentence: native numbers for the hour (+ 시, si) and Sino-Korean for the minutes (+ 분, bun).
- 세 시 삼십 분se si samsip bun
3:30
세 (native 3) + 시 for the hour; 삼십 (Sino-Korean 30) + 분 for the minutes.
- 일곱 시 십오 분ilgop si sibo bun
7:15
일곱 (native 7) for the hour; 십오 (Sino-Korean 15) for the minutes.
Numbers, counters, days, and dates are pure memorization — exactly the kind of material that sticks fastest with spaced repetition. Our vocabulary deck drills these high-frequency sets so both number systems and the calendar words become automatic, instead of something you stop and calculate. If you're still building the basics, our self-study Korean roadmap shows where numbers fit into an efficient beginner plan.
Make numbers automatic
Drill both Korean number systems, the days, and the months with spaced-repetition flashcards until they're instant.
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