Korean Ordinal Number Converter

Cardinal numbers, written as Korean ordinals

Korean has two number systems, and so it has two ways to form ordinals. The native system adds 째 to native cardinals for counting (‘the third child’), while the Sino-Korean system prefixes 제 to Sino-Korean numbers for chapters, ranks, and formal order. This tool produces both, so you can pick the one that fits your sentence.

How it works

For native ordinals, the cardinal is built from the native ones (하나, 둘, 셋 …) and tens (열, 스물, 서른 …), then 째 is attached. The first is special — it uses the stem 첫 to give 첫째. Inside compounds the ones contract before 째 just as they do before counters, so eleventh is 열한째 and twenty-second is 스물두째.

For Sino-Korean ordinals, the number is rendered in Sino-Korean (일, 이, 삼 …, grouped every ten-thousand by 만, 억) and the prefix 제 is added:

3rd native = 셋째
3rd Sino   = 제삼   (also written 제3)
22nd native = 스물두째

Native vs. Sino-Korean ordinals: when to use which

The two ordinal systems are not interchangeable. Choosing the wrong one sounds unnatural or changes the register significantly.

Use native Korean ordinals (첫째, 둘째…) when:

• Counting through people: 첫째 아이 (the first child), 둘째 아들 (the second son).
• Listing items informally: 첫째로, 둘째로 (first of all, second of all) in spoken explanations.
• Talking about birth order, siblings, or turns in a game.
• The number is small (1–99) and the context is everyday or conversational.

Use Sino-Korean ordinals (제1, 제2 / 제일, 제이) when:

• Labelling chapters, episodes, sections: 제1장 (Chapter 1), 제3편 (Part 3).
• Referring to editions, versions: 제2판 (second edition).
• Listing formal rankings: 제1위 (first place).
• The number is large (above 99) — native ordinals are not used for large values.
• Written or formal register.

The irregular first ordinal

In the native system, “first” does not come from 하나 the way 둘째 comes from 둘. Instead it uses the special stem 첫: 첫째 (first). This stem also appears in 첫날 (the first day), 첫사랑 (first love), and 첫인상 (first impression).

From 둘째 onward, native ordinals are regular: the cardinal plus 째, with the usual contractions for the ones digits before the suffix (하나→한, 둘→두, 셋→세, 넷→네, 스물→스무 before 째).

Examples

Because native numerals fade out past 99, large ordinals are practically always Sino-Korean. For a plain cardinal in either system, use the Korean Number to Words tool.