Korean Numbers: Native Korean and Sino-Korean Systems

Learning Korean numbers is your first major step into thinking like a Korean speaker. Unlike English, Korean uses two distinct number systems—Native Korean and Sino-Korean—for different everyday situations. Mastering which system to use and when is not just a grammar rule; it’s essential for clear communication when counting objects, telling time, handling money, or stating your age.

The Two Parallel Number Systems

Korean employs two sets of numbers because of its historical and linguistic development. Native Korean numbers are indigenous to the Korean language. They are generally used for counting a small number of items (1-99) and are always paired with specific counting words. The basic set you must memorize is: 하나 (hana) for one, 둘 (dul) for two, 셋 (set) for three, 넷 (net) for four, 다섯 (daseot) for five, 여섯 (yeoseot) for six, 일곱 (ilgop) for seven, 여덟 (yeodeol) for eight, 아홉 (ahop) for nine, and 열 (yeol) for ten.

In contrast, Sino-Korean numbers are derived from Chinese characters. This system is used for dates, money, phone numbers, addresses, and any number above 99. The first ten are: 일 (il) for one, 이 (i) for two, 삼 (sam) for three, 사 (sa) for four, 오 (o) for five, 육 (yuk) for six, 칠 (chil) for seven, 팔 (pal) for eight, 구 (gu) for nine, and 십 (sip) for ten. The pattern is highly systematic, making larger numbers logical to construct (e.g., 이십 is twenty, 삼백 is three hundred).

Context Dictates the System

Choosing the correct system is not random; it is strictly governed by context. You can think of it as having two different tools for two different jobs. Native Korean is primarily used for counting physical objects and indicating age. For example, if you want two apples, you would use Native Korean: 사과 두 개 (sagwa du gae).

Sino-Korean is the default for mathematics, dates, measurements, phone numbers, and any number involving currency. For instance, a phone number is recited digit-by-digit using Sino-Korean: 공일공-이삼사오-육칠팔구 (010-2345-6789). Years, months, and days of the month also use Sino-Korean: 2025년 3월 15일 (이천이십오년 삼월 십오일). This clear division is the cornerstone of using Korean numbers correctly.

Counting with Classifiers

When counting objects with Native Korean numbers, you must use a counter or classifier, similar to Chinese measure words. The generic counter for most inanimate objects is 개 (gae). The number and the counter are connected by the Native Korean numeral in its modified form. The first four numbers change slightly when used before a classifier: 하나 becomes 한, 둘 becomes 두, 셋 becomes 세, and 넷 becomes 네. So, "three books" is 책 세 권 (chaek se gwon), where 권 is the counter for books.

Other common classifiers include 명 (myeong) for people, 마리 (mari) for animals, and 병 (byeong) for bottles. The rule is simple: Native Korean number (in its modified form) + Counter. For quantities over 99, you switch to Sino-Korean numbers but still use the counter (e.g., 책 백 오 권 for 105 books).

Practical Application: Money, Time, and Age

These three areas perfectly illustrate the interplay between the two systems.

• Money: The Korean Won (₩) uses Sino-Korean numbers exclusively. ₩1,500 is 천오백원 (cheon-obaek won). When paying at a store, you will always use this system.
• Time: Telling time combines both systems. The hour is expressed using Native Korean numbers with the counter 시 (si). The minutes use Sino-Korean numbers with the counter 분 (bun). Therefore, 2:30 is 두 시 삼십 분 (du si samsip bun).
• Age: Age is typically stated using Native Korean numbers with the counter 살 (sal). "I am twenty years old" is 저는 스무 살이에요 (jeoneun seumu sarieyo). Note that 스물 (seumul), the Native Korean word for twenty, also shortens to 스무 before a counter. For formal documents or legal age, Sino-Korean may be used.

Common Pitfalls

1. Mixing systems within a single context: A classic error is using Native Korean for minutes or Sino-Korean for hours when telling time. Remember the formula: Native Korean hours, Sino-Korean minutes. Similarly, don't use Native Korean numbers for money amounts.
2. Forgetting the counter with Native Korean numbers: Saying "사과 둘" instead of "사과 두 개" is a tell-tale sign of a beginner. The counter is not optional when counting discrete items with the Native system.
3. Misusing the modified forms of 1, 2, 3, and 4: Using 하나 개, 둘 명, or 셋 병 is incorrect. You must use the modified forms: 한 개, 두 명, 세 병. This rule applies only to these first four Native Korean numbers.
4. Using Native Korean for large quantities: Native Korean numbers are cumbersome beyond 99. While you can say Native Korean numbers up to 99, for any practical purpose with large numbers—like 10,000 Won or the year 2000—you must default to the Sino-Korean system.

Summary

• Korean has two number systems: Native Korean (for counting items and age) and Sino-Korean (for dates, money, phone numbers, and large numbers).
• The system you use is determined by context, not the number itself. Dates, math, and currency always use Sino-Korean.
• When counting objects with Native Korean numbers, you must pair them with a relevant counter or classifier (e.g., 개 for things, 명 for people).
• The first four Native Korean numbers (1, 2, 3, 4) change form when used before a counter (하나 → 한, 둘 → 두, etc.).
• Practical applications like telling time combine both systems (Native hours, Sino minutes), while stating age primarily uses Native Korean and money exclusively uses Sino-Korean.