Two number systems: Sino-Korean and native Korean
Korean has two sets of numbers, and you need both every day. Sino-Korean numbers come from Chinese: 일, 이, 삼, 사, 오 (il, i, sam, sa, o). Native Korean numbers are the original Korean words: 하나, 둘, 셋, 넷, 다섯 (hana, dul, set, net, daseot).
The rule of thumb: native numbers are for counting (things, people, hours, age), Sino-Korean numbers are for measuring and labeling (money, minutes, dates, phone numbers, floors, units like kg and km). Native numbers only go up to 99. After that, everyone switches to Sino-Korean.
How Sino-Korean numbers are built
You only need ten digits and a few place words: 십 (10), 백 (100), 천 (1,000) and 만 (10,000). Say the digit, then the place: 3,500 is 삼천오백 (samcheonobaek), “three thousand five hundred”. When the digit is 1, drop it: 10 is 십, not 일십, and 1,000 is 천.
Thinking in 만 (ten thousands)
This is the part that trips up most learners. Korean groups big numbers by four digits, not three. After 만 (10⁴) comes 억 (10⁸, 100 million) and then 조 (10¹², one trillion). So 50,000 is “five 만” (오만), 1,000,000 is “a hundred 만” (백만) and 300,000,000 is “three 억” (삼억).
A quick trick: move the comma. Write 123,456,789 as 1|2345|6789, then read each block with its unit: 일억 이천삼백사십오만 육천칠백팔십구. Korean spelling rules put a space after each 만 unit, which is why the converter shows the spaces.
Watch the 1s here too: 만 drops 일 when it stands alone (10,000 = 만), but 억 and 조 always keep it (일억, 일조). After 억 or 조, 만 keeps its 일 as well: 100,010,000 is 일억 일만.
Money, age and time
Money is always Sino-Korean plus 원: ₩25,000 is 이만 오천 원 (iman ocheon won). Prices in shops are often written in a mix like 2만 5천원, so it helps to recognize 만 at a glance.
Age uses native numbers with 살 in conversation (스물다섯 살), and Sino-Korean with 세 on forms and in the news (이십오 세).
Time mixes both systems in one sentence: hours are native, minutes are Sino-Korean. 3:30 is 세 시 삼십 분 (se si samsip bun). You can also say 세 시 반 (half past three).
Counter forms: 한, 두, 세, 네, 스무
Before a counter word such as 개 (items), 명 (people) or 살 (years old), five native numbers get shorter: 하나 → 한, 둘 → 두, 셋 → 세, 넷 → 네 and 스물 → 스무. The change also applies inside bigger numbers: 12 people is 열두 명 and 24 years old is 스물네 살.
Common mistakes
- Saying 일만 for 10,000. In speech it is just 만. 일만 belongs on checks and bank forms.
- Forgetting 일 before 억. 100 million is 일억, not 억.
- Mixing up the clock. 세 시 is three o'clock, but 삼 분 is three minutes. 삼 시 sounds wrong to Koreans.
- Reading spelling instead of sound. 십육 (16) is pronounced [심뉵] simnyuk and 백만 is [뱅만] baengman. The romanization on this page follows the real sound.
- Using native numbers above 99. 백 (100) has no everyday native equivalent, so 120 items is 백이십 개. You may hear 백스무 개 in casual speech, and 101 to 109 are often said as 백한 개, 백두 개 and so on.
- Translating “million” directly. There is no single word for a million. Think 백만 (100 × 만).