은/는 vs 이/가: The Difference Explained in 4 Simple Rules

은/는 marks the topic, the thing you are talking about. 이/가 marks the subject, and it points at exactly who or what. Textbooks stop there, which is why the two still feel the same. Four simple rules decide most sentences for you.

Level: Beginner · TOPIK 1-2

Both particles come right after a noun, and both often translate to nothing at all in English. That makes them hard to tell apart. This post shows when each one is the natural choice, with examples you can copy.

The Short Answer: 은/는 vs 이/가

은/는 sets the topic: “As for me…” or “Talking about this…”. The important part comes after it.
이/가 picks out the subject: “I am the one.” The important part is the noun itself.

Here is the same sentence with each particle.

The words are almost the same, but the questions they answer are different. 저는 학생이에요 answers “Tell me about yourself.” 제가 학생이에요 answers “Who is the student?”

Part	Meaning
저	I (polite)
는	topic marker (“as for”)
학생	student
이에요	am / is (polite)

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How to Attach Them

Each particle has two forms. Pick one by looking at the last letter of the noun.

Noun ends in	Topic	Subject	Example
a consonant	은	이	책은 / 책이 (book)
a vowel	는	가	친구는 / 친구가 (friend)

A few common words change shape before 가. Learn these four as single words.

• 저 + 가 → 제가 (I, polite)
• 나 + 가 → 내가 (I, casual)
• 너 + 가 → 네가 (you, casual). In everyday speech, most people say 너가 instead. Use 너가 only with someone your age or younger. You may also hear 니가, but that is only for very close friends or younger siblings (couples sometimes use it playfully, or in an argument). Anywhere else, 니가 sounds rude.
• 누구 + 가 → 누가 (who)

With 은/는 nothing changes: 저는, 나는, 너는.

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Four Rules That Decide for You

Instead of thinking “topic or subject?”, ask these four questions. They cover most everyday sentences.

Rule 1: Introducing yourself or a topic uses 은/는

When you start talking about something and then describe it, use 은/는. This is why self-introductions start with 저는.

Native tip: introducing yourself politely
In real conversation, Koreans often drop 저는 and just say their name. When they do, they usually switch to the more formal -입니다 to stay polite. When you meet someone for the first time in a formal setting, -입니다 is the most polite choice.

처음 뵙겠습니다. 에밀리입니다.
cheoeum boepkkesseumnida. emilli-imnida.
Nice to meet you. I’m Emily.

저는 에밀리예요 is fine in everyday situations, and people will understand it from a learner. It is just less formal than 에밀리입니다.

Rule 2: Question words and their answers use 이/가

Words like 누가 (who) and 뭐가 (what) always take 이/가, and so does the answer. The answer is the new, important part of the sentence.

엄마는 전화했어요 is not wrong grammar, but as an answer it sounds odd. It suggests “Mom called (but someone else didn’t).”

Rule 3: Something new uses 이/가, something known uses 은/는

When a person or thing appears for the first time, use 이/가. Once everyone knows what you mean, switch to 은/는. Korean stories show this clearly.

The same thing happens when you notice something right now: 저기 버스가 와요! (jeogi beoseuga wayo!, “Look, the bus is coming!”).

Rule 4: Inside a describing part, use 이/가

When a small sentence describes a noun (“the food I like“, “the cake my friend made“), the subject inside it takes 이/가. The 은/는 goes on the big topic of the whole sentence.

Part	Meaning
제가 좋아하는	that I like (describing part, so 제가)
음식은	food + topic marker (the topic of the sentence)
떡볶이예요	is tteokbokki

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Words That Always Take 이/가

Some common expressions use 이/가 almost every time. If you memorize these patterns, many sentences become automatic.

Pattern	Example
있다 / 없다 (to have, there is)	시간이 없어요. I don’t have time.
아니다 (to not be)	저는 학생이 아니에요. I’m not a student.
되다 (to become)	의사가 되고 싶어요. I want to become a doctor.
좋다 / 싫다 (to like, to dislike)	저는 고양이가 좋아요. I like cats.
아프다 (to hurt)	머리가 아파요. My head hurts.

Notice 저는 학생이 아니에요 and 저는 고양이가 좋아요. Many Korean sentences use both particles at once: 은/는 for the topic (me) and 이/가 for the part being described.

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A Quick Look at Contrast

은/는 has one more job. It can compare one thing with others, even when the others are not said out loud.

This “unspoken comparison” is something native speakers hear right away, and it changes how polite or direct you sound.

🗣️ Native insight Why does 커피는 마셔요 sound like a “but” is coming? How Koreans use 은/는 to hint, soften, and say no politely. Read the answer →

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Common Mistakes

❌ Wrong	✅ Right	Why
나가 할게.	내가 할게. naega halkke. I’ll do it. (casual)	나 + 가 becomes 내가. (나가 is a different word: “go out.”)
A: 누가 왔어요? B: 민수는 왔어요.	민수가 왔어요. minsuga wasseoyo. Minsu came.	Answers to question words take 이/가.
저는 사는 곳은 서울이에요.	제가 사는 곳은 서울이에요. jega saneun goseun seourieyo. The place I live is Seoul.	The describing part takes 이/가.

🗣️ Try It Today

Pick one and use it with a Korean friend today.

저는 아이스 아메리카노요.
jeoneun aiseu amerikanoyo.
I’ll have an iced Americano.

이 근처에 편의점 있어요?
i geuncheoe pyeonijeom isseoyo?
Is there a convenience store near here? (In speech, Koreans often drop 이/가 here.)

뭐가 제일 맛있어요?
mwoga jeil masisseoyo?
What’s the best thing here?

제가 할게요.
jega halkkeyo.
I’ll do it.

저는 괜찮아요.
jeoneun gwaenchanayo.
I’m fine. / No thanks, I’m good.

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Summary and Quick Quiz

	은/는	이/가
Basic job	Sets the topic	Picks out the subject
Introducing yourself	✅ 저는…	❌
Who? What? and the answer	❌	✅ 누가, 뭐가
New vs known	Already known	New, just appeared
Inside a describing part	❌	✅ 제가 좋아하는…
Extra meaning	Contrast (“this one, at least”)	Focus (“this one, not another”)