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

은/는 and 이/가 are not interchangeable versions of the same subject marker. They organize information differently.

• 은/는 sets a topic or creates contrast: “as for…”
• 이/가 marks the subject and often puts focus on it

That is why the same noun can appear with either one without either sentence being wrong.

Start with the free 은/는 grammar reference, then use the particle checker to test your own examples.

The fastest practical rule

Ask two questions:

1. Am I setting up what I want to talk about or contrasting it? → 은/는
2. Am I identifying who or what is the answer, new information, or the focused subject? → 이/가

Compare:

The English translation looks similar, but the focus is different.

은/는 for topics and contrast

Use 은 after a final consonant and 는 after a vowel.

• 책은 재미있어요. → As for the book, it is interesting.
• 저는 커피를 좋아해요. → As for me, I like coffee.
• 커피는 좋아하지만 차는 안 좋아해요. → I like coffee, but I do not like tea.

Once one thing is marked with 은/는, listeners often expect a comment or comparison about that topic.

이/가 for focus and new information

Use 이 after a final consonant and 가 after a vowel.

If someone asks 누가 왔어요? (Who came?), a natural answer is 민지가 왔어요. Minji is exactly the missing information, so 가 puts the focus there.

The same pattern appears with many existence statements:

• 책이 있어요. → There is a book.
• 시간이 없어요. → There is no time / I do not have time.

See the related 있어요/없어요 reference.

One noun can use both

• 비빔밥이 맛있어요. → Bibimbap is delicious. Bibimbap is the focused answer.
• 비빔밥은 매워요. → As for bibimbap, it is spicy. Bibimbap is now the established topic.

This is why memorizing “topic vs subject” is only the first step. You also need to notice what information is already known and what the speaker highlights.

Mini practice

Choose the more natural particle for the intended meaning.

1. “Who is the teacher?” → 제가 선생님이에요.
2. “As for today, it is cold.” → 오늘은 추워요.
3. “What is delicious?” → 김치가 맛있어요.
4. “I like coffee, but not tea.” → 커피는 좋아하지만 차는 안 좋아해요.

What to study next

• Complete Korean particles guide
• 을/를 object marker
• 에 vs 에서
• Particle checker
• Free grammar map

The goal is not to explain every nuance before you speak. Make the common choices automatic first, then refine them as you hear more Korean.