TOPIK GUIDE · Korean grammar made clear
You learn that 은/는 marks the topic and 이/가 marks the subject. Then you see 저는 학생이에요 and 제가 학생이에요. Both can mean “I am a student.” So what actually changes?
The missing piece is context: what the speakers are talking about, what the listener already understands, and what the speaker wants to communicate now. The particles help organize that information. English often shows the same difference through word stress, word order, or an extra phrase.
This guide starts with one clear distinction and builds from it. You will learn when one particle is the natural choice, when both are possible, and why changing the particle can change the message even when the English translation stays the same.
The core distinction
은/는: sets up something to talk about, or contrasts it with something else. Think: “Speaking of X…” or “As for X…”
이/가: usually marks the grammatical subject. It can neutrally present an event or state, or identify who or what fits the description.
These are different jobs. They are not two interchangeable versions of the English word “is.”
1. First, choose the correct form
There are two decisions: which particle family you need, and which form matches the preceding word. The final sound decides the form; it does not decide the meaning.
| The preceding word ends in… | Topic / contrast | Subject |
|---|---|---|
| A consonant (받침) | 은: 학생은, 책은 | 이: 학생이, 책이 |
| A vowel (no 받침) | 는: 저는, 학교는 | 가: 제가, 학교가 |
학생 ends in ㅇ, so use 학생은 or 학생이. 학교 ends in a vowel, so use 학교는 or 학교가. Attach the particle directly to the word, without a space.
Learn these common pronoun forms as complete units:
| Pronoun | With 은/는 | With 이/가 |
|---|---|---|
| 저 — I, polite/humble | 저는 | 제가 |
| 나 — I, casual | 나는 | 내가 |
| 너 — you, casual | 너는 | 네가 |
| 누구 — who | 누구는 | 누가 |
누구는 exists, especially in contrasts such as “some people…others…,” but the normal subject question “Who…?” uses 누가. In conversation, 네가 is often pronounced like 니가 to distinguish it from 내가; the standard written form is 네가.
2. Topic and subject: two different questions
The subject: who or what does something, or has a certain state?
In “Mina is sleeping,” Mina is the subject. In “The room is small,” the room is the subject. A subject does not have to perform an action; it can have a quality or be in a state.
미나가 자요.
Mina is sleeping.
방이 작아요.
The room is small.
가 and 이 mark the subjects of “sleep” and “be small.” Neither sentence needs to emphasize “Mina alone” or “this room alone.”
The topic: what are we talking about?
A topic is the person, thing, time, or situation that the speaker uses as the starting point. The rest of the sentence says something about it.
미나는 대학생이에요.
Mina is a university student.
Topic: Mina. Information about her: she is a university student.
오늘은 날씨가 좋아요.
The weather is nice today.
Topic/frame: today. Subject of “is nice”: the weather. Today is not the thing that has nice weather as a grammatical subject; it sets the time we are discussing.
A word can be both the topic and the person doing the action. In 미나는 자요, Mina still does the sleeping. Using 는 does not remove that relationship; it presents Mina as the topic or contrasts her with someone else.
Grammar note: the National Institute of Korean Language classifies 이/가 as a subject case particle and 은/는 as an auxiliary particle with topic, contrast, and emphasis uses. This is why “two kinds of subject marker” is an incomplete explanation. See the institute’s explanation (Korean).
3. The clearest comparison: 저는 vs 제가
Imagine two different situations. The fact stays the same: you are a teacher. Your reason for saying it changes.
Situation A · Introducing yourself
안녕하세요. 저는 한국어 선생님이에요.
Hello. I am a Korean language teacher.
You set yourself up as the topic and tell the listener something about yourself: “As for me, I am a Korean teacher.” This is a natural first introduction, even if you have never met the listener.
Situation B · Identifying the teacher
A: 누가 한국어 선생님이에요?
B: 제가 한국어 선생님이에요.
A: Who is the Korean language teacher?
B: I am the Korean language teacher.
The missing information is the person’s identity. 제가 fills that gap: “I’m the one.”
Notice what did not change: your identity, your job, and the polite ending. What changed was the question your sentence answered.
A useful question to ask yourself: Am I saying something about this person, or am I identifying which person it is?
This works especially well with short sentences about people. It is a guide, not a rule for every possible Korean sentence.
4. When to use 은/는
A. Introduce or continue a topic
저는 인도에서 왔어요.
I am from India.
제 동생은 대학생이에요.
My younger sibling is a university student.
이 책은 한국어 문법을 쉽게 설명해요.
This book explains Korean grammar simply.
The speaker chooses “me,” “my younger sibling,” or “this book” as the thing to discuss. The topic may already be familiar, but it can also be introduced now if the listener can understand what the speaker means.
B. Make a general statement
고양이는 잠을 많이 자요.
Cats sleep a lot.
겨울은 추워요.
Winter is cold.
운동은 건강에 좋아요.
Exercise is good for your health.
Here the speaker talks about a whole category or a general topic. But 은/는 does not itself mean “in general.” 이 고양이는 잠을 많이 자요 means “This cat sleeps a lot”: one particular cat is the topic.
C. Contrast two things
저는 커피를 좋아해요. 동생은 차를 좋아해요.
I like coffee. My younger sibling likes tea.
오늘은 바빠요. 내일은 괜찮아요.
I’m busy today. Tomorrow works for me.
커피는 마셔요. 술은 안 마셔요.
I drink coffee. I don’t drink alcohol.
The last example is especially useful. Coffee and alcohol are the things being drunk—the objects, not the subjects. 은/는 can mark a contrast on an object too.
Compare 커피를 마셔요 (“I drink coffee”) with 커피는 마셔요 (“Coffee, I do drink”). In this basic pattern, 는 takes the place of 를. Do not write 커피를는.
D. Suggest a contrast without saying the other half
음식은 맛있어요.
The food is good.
In a restaurant review, this can suggest “The food is good, but perhaps the service or price is less good.” It can also simply introduce the food as the topic. The situation and tone decide.
한국어는 할 수 있어요.
I can speak Korean.
When someone asks about several languages, this can mean “Korean, I can speak.” The speaker is not making the same claim about every other language.
Do not add an imaginary “but” to every 은/는 sentence. 저는 학생이에요 is a normal self-description. It does not automatically mean “I am a student, unlike you.” Contrast needs support from context.
5. When to use 이/가
A. Present an event or something you notice
비가 와요.
It’s raining.
전화가 왔어요.
A phone call came in.
밖에 사람이 있어요.
There is someone outside.
You are presenting what is happening or what exists. The whole situation may be the new information. You are not necessarily selecting one subject against alternatives.
B. Answer “who?” or “what?” when it asks for the subject
A: 누가 왔어요?
B: 지수가 왔어요.
A: Who came?
B: Jisu came.
A: 뭐가 필요해요?
B: 여권이 필요해요.
A: What do you need?
B: I need a passport.
The answer identifies the missing person or thing. Even if everyone already knows Jisu, 지수가 is natural here. The person is familiar; the information that Jisu is the person who came is new.
Check the role of the question word. 누구를 만났어요? means “Who did you meet?” Here “who” is the object, so a normal answer is 지수를 만났어요, not 지수가 만났어요.
C. Correct an identity or volunteer
A: 민수가 만들었어요?
B: 아니요. 지수가 만들었어요.
A: Did Minsu make it?
B: No. Jisu made it.
A: 누가 발표할 거예요?
B: 제가 할게요.
A: Who is going to give the presentation?
B: I’ll do it.
Here 이/가 helps identify the relevant person. English might stress “Jisu made it” or “I’ll do it.” But 이/가 does not always mean “only.” 지수가 왔어요 does not, by itself, say nobody else came.
D. Introduce someone or something into a story
공원에 강아지가 있었어요. 그 강아지는 아주 작았어요.
There was a puppy in the park. The puppy was very small.
First, the puppy enters the story with 가. Then it becomes the topic with 는.
This is the source of the helpful “new information → 이/가; known topic → 은/는” pattern. The mistake is treating this story pattern as a universal rule.
6. Why both particles appear in one sentence
Because a topic and a subject are different jobs, one sentence can contain both.
저는 한국어가 재미있어요.
I find Korean interesting.
저는: as for me / from my point of view.
한국어가: Korean is the thing that is interesting.
이 식당은 음식이 맛있어요.
The food at this restaurant is delicious.
이 식당은: as for this restaurant.
음식이: its food is what tastes delicious.
제 동생은 키가 커요.
My younger sibling is tall.
제 동생은: my younger sibling is the topic.
키가: height is the subject of 커요.
English often restructures these sentences. You do not need to translate “as for” every time. Use that phrase to understand the Korean structure, then translate naturally.
A productive pattern: A은/는 B이/가 + description.
Talk about A, then describe a related part, quality, or experience B: a restaurant and its food; a person and their height; a person and something they find interesting.
This is a common pattern, not a rule that 은/는 must always come before 이/가 in every sentence.
7. Common patterns that English can make confusing
좋아요 vs 좋아해요
저는 한국 음식이 좋아요.
I like Korean food.
좋다 means “to be good/pleasing.” Korean food is what is pleasing to me, so 이 marks it.
저는 한국 음식을 좋아해요.
I like Korean food.
좋아하다 means “to like.” Korean food is the object of liking, so 을 marks it.
The English translation is the same, but the Korean grammar is different. Learn the sentence pattern with the word. 저는 한국 음식은 좋아해요 is also possible when contrasting Korean food with other food: “Korean food, I do like.”
있어요 and 없어요
저는 시간이 있어요.
I have time.
가방에 책이 없어요.
There is no book in the bag.
The thing that exists, is available, or is absent commonly takes 이/가. But contrast is still possible: 시간은 있어요 can mean “I do have time,” perhaps with money or energy as a separate issue. There is no rule that 있어요 must always be preceded by 이/가.
필요해요
도움이 필요해요.
I need help.
Korean expresses this as “Help is needed.” That is why the neutral pattern uses 도움이, even though English treats “help” as the object of “need.”
아니에요 and 되다
저는 학생이 아니에요.
I am not a student.
민수는 의사가 됐어요.
Minsu became a doctor.
Memorize N이/가 아니에요 (“is not N”) and N이/가 되다 (“become N”). In traditional Korean school grammar, 이/가 in these patterns is classified as a complement particle, not a subject particle. You do not need the technical term to use the patterns correctly.
Compare 저는 학생이에요 (“I am a student”). The 이 inside 이에요 belongs to the form of 이다; it is not a separate subject particle. Do not divide every visible 이 into the same grammatical category.
Contrast can appear here too: 학생은 아니에요 means “I’m not a student,” with “student” contrasted against other possible identities.
8. Six sentence pairs: what changes?
Both versions below can be grammatical. The suggested situations show why a speaker might choose one.
Pair 1: 민수는 왔어요 / 민수가 왔어요
민수는 왔어요.
Minsu came.
We are checking several guests: “Minsu came, at least.” Or we have moved on to discussing Minsu. His attendance is the information about that topic.
민수가 왔어요.
Minsu came / Minsu is here.
Someone asks who came, or you announce Minsu’s arrival. The sentence can identify him or simply report the event.
Pair 2: 오늘은 좋아요 / 오늘이 좋아요
오늘은 좋아요.
Today works for me.
You consider today as an option, perhaps in contrast with tomorrow.
오늘이 좋아요.
Today is a good choice.
Someone asks which day works best. You identify today as the suitable day.
The difference can be small. In scheduling conversations, both can be natural; the first frames today as the topic or contrast, while the second identifies the day.
Pair 3: 이 책은 좋아요 / 이 책이 좋아요
이 책은 좋아요.
This book is good.
You are reviewing this book, or saying this one is good in contrast with other books.
이 책이 좋아요.
This book is good / I like this book.
You choose a book from several options, or express that this book appeals to you. The exact English translation depends on the situation.
Pair 4: 비는 와요 / 비가 와요
비는 와요.
It is raining, though.
A contrast is available: perhaps it is raining, but the wind is not strong, so the outing may still be possible.
비가 와요.
It is raining.
You look out of the window and report the weather. This is the neutral choice for that situation.
Pair 5: 저는 갈게요 / 제가 갈게요
저는 갈게요.
I’ll go.
You state your own plan, perhaps while other people stay. In a suitable situation, it can also mean “I’ll be going now.”
제가 갈게요.
I’ll go.
You volunteer to be the person who goes: “I’ll take that role.”
Pair 6: 사과는 맛있어요 / 사과가 맛있어요
사과는 맛있어요.
Apples are delicious / The apples are delicious.
You describe apples in general, or discuss the apples among the fruit on the table.
사과가 맛있어요.
The apples are delicious.
You taste the fruit and react, or identify apples as the delicious option when someone asks which fruit is good.
Do not turn the last pair into “은/는 means all apples; 이/가 means one apple.” Number and general meaning depend on more than the particle.
9. Five shortcuts that need limits
| Tempting shortcut | A more reliable understanding |
|---|---|
| “은/는 is old information; 이/가 is new information.” | This describes a common story pattern. A new topic can take 은/는, and a familiar person can take 이/가 when their identity answers the question. |
| “은/는 emphasizes what comes after it; 이/가 emphasizes what comes before it.” | This can help with topic-comment vs identity answers. But 이/가 also occurs in neutral event reports, and 은/는 can strongly contrast the word before it. |
| “이/가 means only this one.” | It can identify a person among alternatives. It does not automatically exclude everyone else. Use expressions such as 만 when you actually need “only.” |
| “은/는 is general; 이/가 is specific.” | General descriptions often use 은/는, but specific people and objects can be topics too: 이 책은 재미있어요. |
| “A sentence always has one correct choice.” | Sometimes structure strongly favors one form. Often both work, with different context or emphasis. |
Also, neither particle means English “a” or “the.” The puppy story resembles “a puppy → the puppy,” but Korean particles and English articles do different jobs.
10. Longer sentences: look inside each clause
A clause is a small sentence-like unit inside a larger sentence. In a neutral description, the subject inside a clause often takes 이/가.
제가 어제 산 책은 재미있어요.
The book I bought yesterday is interesting.
Inside 제가 어제 산 (“that I bought yesterday”), 제가 marks who bought it. The whole phrase 제가 어제 산 책은 sets “the book I bought yesterday” as the topic of the main statement.
저는 동생이 오면 출발할 거예요.
I will leave when my younger sibling arrives.
저는 is the main topic. Inside 동생이 오면 (“when my younger sibling arrives”), 동생이 is the subject of arriving.
Do not choose the particle by counting nouns from the start of the sentence. First find which words belong together. 은/는 can appear inside some clauses for a special topic or contrast, but 이/가 is a useful default for a neutral subject in a noun-modifying clause such as “the book that I bought.”
은/는 can also attach after other particles
학교에서는 한국어를 써요.
At school, I use Korean.
에서 marks where the action happens; 는 makes that location a topic or contrast, perhaps against home.
저에게는 시간이 없어요.
As for me, I don’t have time.
에게 establishes the relation to me; 는 adds topic or contrast.
With subject 이/가 and object 을/를, 은/는 normally replaces the case particle in the basic patterns discussed here. With particles such as 에, 에서, and 에게, it can follow them: 에는, 에서는, 에게는.
11. What happens in real conversation?
Korean speakers often leave out a subject or topic that is obvious. They may also omit a particle when the role remains clear.
A: 민수 씨는 어디에 가요?
B: 도서관에 가요.
A: Minsu, where are you going?
B: I’m going to the library.
B does not need to say 저는 again.
시간 있어요?
Do you have time?
In everyday speech, this is a common version of 시간이 있어요?.
Omission does not make the particles meaningless. If the point is a contrast or an identity correction, keeping the particle can make that meaning clearer. For learning and careful writing, first understand the complete pattern; then notice where speakers naturally shorten it.
12. A practical way to choose
- Check the sentence pattern. Is the word a subject, an object, or part of a pattern such as 학생이 아니에요? Do not choose only from the English translation.
- Ask what the conversation needs. If you are identifying who or what fits a description, 이/가 is often natural: 누가 왔어요? → 지수가 왔어요.
- Ask whether you are reporting a whole event. For a neutral announcement such as “It’s raining,” use 비가 와요.
- Ask whether you are setting a topic or making a contrast. 은/는 is often natural: 저는 학생이에요; 오늘은 바빠요.
- If both work, choose the meaning you want. A change in particle may be a change in perspective, not a correction of bad grammar.
For TOPIK reading and writing
Read the surrounding sentences before deciding. Look for a newly introduced person, a continuing topic, an answer identifying someone, or a contrast between two groups. In writing, establish a topic clearly, but avoid starting every sentence with 저는 when the reader already knows who you mean.
Practice with short connected passages. A sentence copied alone often hides the very information that explains the particle.
저는 한국어를 공부해요. 한국어는 재미있지만 발음이 어려워요. 그래도 매일 연습해요.
I study Korean. Korean is interesting, but the pronunciation is difficult. Still, I practice every day.
First 저는 introduces the speaker as the topic. Then 한국어는 shifts the topic to Korean. 발음이 marks what is difficult. The final sentence leaves out “I” because it is clear.
13. Practice: choose for the situation
Choose from 은, 는, 이, and 가. Use the context given. Some questions deliberately allow more than one interpretation; explaining the difference is part of the practice.
- You introduce yourself: 안녕하세요. 저___ 리나예요.
Hello. I’m Rina. - A: 누가 창문을 열었어요? B: 민수___ 열었어요.
Who opened the window? Minsu did. - You notice falling snow: 눈___ 와요!
It’s snowing! - You contrast your schedule: 오늘___ 바빠요. 내일___ 괜찮아요.
I’m busy today. Tomorrow works. - You describe the food at a restaurant: 이 식당___ 음식___ 맛있어요.
- A neutral statement of what you need: 여권___ 필요해요.
I need a passport. - You volunteer when someone asks who will help: 저___ 도와줄게요.
I’ll help. - A neutral description: 이것은 동생___ 만든 케이크예요.
This is the cake my younger sibling made. - Complete the standard negative identity pattern: 저는 의사___ 아니에요.
I am not a doctor. - You contrast drinks: 커피___ 마시지만 술___ 안 마셔요.
I drink coffee, but I don’t drink alcohol. - Choose either particle family, then explain a context: 이 책___ 좋아요.
- Introduce a cat into a story, then describe it: 집 앞에 고양이___ 있었어요. 그 고양이___ 아주 작았어요.
Show answers 1–4: introductions, identification, events, contrast
1. 저는. You make yourself the topic of a self-introduction. 제가 would fit a different situation, such as identifying yourself as the Rina someone is looking for.
2. 민수가. The question asks who opened the window. Minsu is the identity that fills the gap. 민수는 could introduce a contrast, but it is not the straightforward identity answer requested here.
3. 눈이. You report the event you notice. 눈은 would need a topic or contrast context.
4. 오늘은 / 내일은. You explicitly contrast two days.
Show answers 5–8: structure and clauses
5. 이 식당은 음식이 맛있어요. The restaurant is the topic; its food is what tastes delicious.
6. 여권이. In this pattern, the passport is what is needed. 여권은 would make the passport a topic or contrast.
7. 제가. You identify yourself as the person who will help. 저는 도와줄게요 can state your own intention or contrast you with others, but 제가 directly fits the invitation to volunteer.
8. 동생이. The younger sibling is the subject inside 만든, “made,” which describes the cake. 은 would introduce a special contrast rather than the neutral description requested.
Show answers 9–12: patterns and flexible choices
9. 의사가. Use the standard N이/가 아니에요 pattern. 의사는 아니에요 is also grammatical when contrasting “doctor” with another identity.
10. 커피는 / 술은. These are contrasted objects. 은/는 is not restricted to subjects.
11. 이 책은 / 이 책이. Both work. 이 책은 좋아요 reviews this book as a topic or contrasts it with others. 이 책이 좋아요 can identify this book as your choice, or express that you like it.
12. 고양이가 / 그 고양이는. First introduce the cat’s presence, then use that cat as the topic of the next description. Notice that 고양이 ends in a vowel: 고양이 + 가 = 고양이가.
14. Frequently asked questions
Are 은/는 and 이/가 interchangeable?
Sometimes either is grammatical, but they present the information differently. 민수는 왔어요 discusses or contrasts Minsu; 민수가 왔어요 can identify who came or announce his arrival. In other cases, the grammatical pattern limits the choice.
Is 저는 more polite than 제가?
No. Both use the humble pronoun 저. Their difference is topic/contrast versus subject marking. Compare 나는 with 내가 for the corresponding casual pronoun forms.
Can I begin a conversation with 은/는?
Yes. 저는 리나예요 is a normal first introduction. Topics do not have to be mentioned in an earlier sentence; they need to be understandable as the thing being discussed.
Does a question always use 이/가?
No. 민수 씨는 어디에 살아요? means “Where do you live, Minsu?” or “Where does Minsu live?” depending on whom you are addressing. Minsu is the topic, and the question asks about the place. Compare 누가 서울에 살아요? (“Who lives in Seoul?”), which asks for the subject’s identity.
Can one sentence contain two uses of 은/는?
Yes. 저는 커피는 마셔요 can mean “As for me, I do drink coffee.” 저는 sets the personal topic; 커피는 contrasts coffee with other drinks. Multiple topics or contrasts need a clear context, so do not add them mechanically.
Is 은/는 only used with nouns?
No. These beginner patterns focus on nouns and noun phrases, but contrastive 는 also appears in expressions such as 먹지는 않아요 (“I don’t eat it,” with contrast depending on context) and 비싸기는 해요 (“It is expensive, I admit”). Learn these as separate patterns when you reach them.
How can I stop hesitating while speaking?
Learn short exchanges rather than isolated definitions: 누가 할 거예요? → 제가 할게요; 자기소개를 해 주세요. → 저는…; 오늘은 어때요? → 오늘은 바빠요. Practice one situation repeatedly, then change the people and vocabulary. You are training a conversational choice, not just memorizing a label.
15. Your final reference card
| What you want to do | Useful starting choice | Example |
|---|---|---|
| Say something about a topic | 은/는 | 저는 학생이에요. |
| Contrast people, objects, or times | 은/는 | 오늘은 바빠요. |
| Give a general description | Often 은/는 | 겨울은 추워요. |
| Report an event or presence | Usually 이/가 | 비가 와요. |
| Identify who or what fits | Usually 이/가 | 제가 할게요. |
| Describe part of a larger topic | Often both | 이 식당은 음식이 맛있어요. |
The habit that makes the difference: before asking “Which particle is correct?”, ask “What am I doing with this sentence?”
If you are setting a topic or making a contrast, think 은/는. If you are marking the subject in a neutral report or identifying who or what fits, think 이/가. Then check the sentence pattern and the surrounding conversation.
You do not need a different English translation for every particle choice. You need to understand why a speaker would say that sentence at that moment.
About the explanations: The examples and teaching framework in this guide are original. Labels such as “topic,” “subject,” and “focus” simplify a complex area of grammar; context and intonation can allow more than one reading. For the formal distinction between the particles, see the National Institute of Korean Language’s response on 은/는 and 이/가. The reference supports the grammatical classification, rather than serving as the source of every example above.
