은/는 vs 이/가: Korean Topic and Subject Particles Explained

Use 은/는 to mark what a sentence is about (the topic) or to contrast it with something else. Use 이/가 to mark the subject when it is new information, or when the point is who or what did something. Which form of each particle you pick depends only on whether the word before it ends in a consonant or a vowel.

That is the short answer. The longer answer is that this is a tendency, not a switch you flip. Native speakers sometimes choose either particle for the same sentence, with only a small change in nuance. The patterns below cover what beginners need, and they will get you right most of the time.

Choosing the form: consonant or vowel

Each particle has two forms. Look at the last sound of the word in front of it. If the word ends in a final consonant (받침 batchim), use the form that starts with a vowel. If it ends in a vowel, use the other one.

So it is 물은 and 물이 (water), but 커피는 and 커피가 (coffee). There are no exceptions based on which consonant it is: ㄹ counts as a consonant too, so 서울은 (Seoul), not 서울는.

Because 은 and 이 start with a silent ㅇ, the final consonant of the word slides over and is said at the start of the particle. Spelling and sound differ:

• 책은 is written chaek-eun but said chae-geun
• 물이 is written mul-i but said mu-ri
• 선생님은 is written seonsaengnim-eun but said seon-saeng-ni-meun
• 밥이 is written bap-i but said ba-bi

If you are unsure where a word’s syllable blocks end, our post on Hangul syllable blocks shows how to spot a final consonant at a glance.

The core difference

Think of 은/는 as saying “as for X…” and 이/가 as pointing a finger at X.

은/는 sets the topic. It tells the listener what you are going to talk about, usually something already known or easy to identify. That is why self-introductions use it: 저는 학생이에요 (jeoneun haksaeng-ieyo), “I’m a student,” literally “as for me, (I) am a student.” The new information is the part after the particle.

이/가 marks the subject as the new part. The listener does not know it yet, or you are singling it out from other possibilities. 비가 와요 (biga wayo) means “it’s raining,” literally “rain is coming.” You are reporting an event, and the rain is the news.

A useful test: what question is the sentence answering?

• “What do you do?” → 저는 학생이에요. The topic is me; the answer is “student.”
• “Who is the student here?” → 제가 학생이에요 (jega haksaeng-ieyo), “I’m the student.” The answer is “me,” so the subject gets 가.

Question words always take 이/가

Question words ask for new information by definition, so they take the subject particle, and so does the word that answers them.

• 누가 왔어요? (nuga wasseoyo?) Who came?
• 친구가 왔어요. (chinguga wasseoyo) A friend came.
• 뭐가 문제예요? (mwoga munje-yeyo?) What’s the problem?
• 어디가 아파요? (eodiga apayo?) Where does it hurt?

Note that 누가 is a shortened form of 누구 + 가. You don’t say 누구가 in normal speech. In the same way, 뭐가 is the everyday spoken version of 무엇이 (mueosi), which you will see in writing.

나는 vs 내가, 저는 vs 제가

The words for “I” change shape before 가. This catches almost every beginner.

나가 and 저가 are wrong. Before 가, 나 becomes 내 and 저 becomes 제.

In speech, 네가 (you) sounds almost the same as 내가 (I), so many speakers say 니가 (niga) for “you” in casual talk. You will hear it constantly in K-dramas and songs, but it is a spoken form, not the standard spelling.

Topic forms also shorten in casual speech: 저는 → 전 (jeon), 나는 → 난 (nan), 이것은 → 이건 (igeon), and 이것이 → 이게 (ige). So 이게 뭐예요? (ige mwoyeyo?) is “What is this?”

Contrast: the other job of 은/는

은/는 also marks contrast, and this is where it can appear more than once in a sentence or attach to things that aren’t the subject at all.

• 저는 커피는 마셔요. (jeoneun keopineun masyeoyo) I do drink coffee (but not something else, maybe tea).
• 오늘은 시간이 없어요. (oneureun sigani eopseoyo) I don’t have time today (another day might work).
• 한국어는 조금 해요. (hangugeoneun jogeum haeyo) I speak a little Korean (but not other languages, or not much else).

Notice the last two: 오늘 and 한국어 are not subjects, yet they take 은/는. The particle is saying “as for this one, compared with others.” In speech, a contrastive 은/는 often gets a little extra stress.

This is also why 은/는 can feel “heavy” in the wrong place. If you answer “Is the weather nice?” with 날씨는 좋아요 (nalssineun joayo), a listener may wait for the “but…”: the weather is nice, but something else isn’t. The neutral answer is 날씨가 좋아요.

Both in one sentence

Korean often puts a topic and a subject in the same sentence. The topic frames it; the subject goes with the verb.

• 저는 머리가 아파요. (jeoneun meoriga apayo) I have a headache. Literally “as for me, the head hurts.”
• 코끼리는 코가 길어요. (kokkirineun koga gireoyo) Elephants have long trunks. Literally “as for elephants, the nose is long.”
• 저는 시간이 없어요. (jeoneun sigani eopseoyo) I don’t have time.

Descriptive verbs like 아프다 (to hurt), 있다 (to exist, have), 없다 (to not exist, not have) and 좋다 (to be good) often work this way. 저는 커피가 좋아요 (jeoneun keopiga joayo, I like coffee) uses 가 because the coffee is what “is good.” With the action verb 좋아하다 (to like), coffee is the object instead: 저는 커피를 좋아해요 (jeoneun keopireul joahaeyo). Both are correct.

Sentence pairs that change meaning

Here are pairs where the particle alone changes what you mean.

Some pairs barely differ. 화장실이 어디예요? and 화장실은 어디예요? (hwajangsiri / hwajangsireun eodiyeyo?) both mean “Where is the bathroom?” The second adds a light “and the bathroom, where is it?” feel, as if you just thought of it. Either is fine in a shop.

Common mistakes

1. Wrong form after the last sound. 책는 and 친구은 are errors. Check the final consonant: 책은, 친구는.
2. 나가 or 저가. Always 내가 and 제가.
3. 은/는 with question words. In ordinary questions it is 누가, 뭐가, 어디가, not 누구는 or 뭐는.
4. Saying 저는 in every sentence. Once the topic is clear, Korean drops it. Starting each sentence with 저는 sounds like constant contrast: “I, on the other hand…”
5. Treating the “rule” as absolute. If you hear a native speaker use the “other” particle, they are probably adding contrast or framing, not making a mistake.

The quickest way to absorb these is through lots of short sentences. The Korean vocabulary flashcards give you nouns to practice with: try saying each word with 은/는 and 이/가 and check the sound change. For the other side of the sentence, the verb endings, see our guide to Korean politeness levels.

Sources: National Institute of Korean Language (국립국어원), Standard Korean Language Dictionary (표준국어대사전) entries for 은, 는, 이 and 가; Ho-min Sohn, The Korean Language (Cambridge University Press, 1999).

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