은/는 vs 이/가: What's the Difference?
The question that follows every Korean learner from day one to intermediate.
Both 은/는 and 이/가 can sit right after the same noun, and both often get translated into English as nothing at all. So 저는 학생이에요 and 제가 학생이에요 both come out as "I am a student" — which makes it look like the choice doesn't matter.
It does. The two particles do completely different jobs. 은/는 tells the listener what you are talking about. 이/가 tells the listener which one specifically you mean.
Quick Summary
은/는 sets the topic ('as for X...'). 이/가 identifies the subject ('it is X that...').
| Particle | Core Meaning | Used With | Example |
|---|---|---|---|
| 은/는 (eun/neun) | Topic / Contrast | Known info, general truths, comparisons, self-introductions | 저는 학생이에요 As for me, I'm a student |
| 이/가 (i/ga) | Subject / Identification | New info, question words, 있다/없다, descriptive verbs | 누가 왔어요? Who came? |
When to Use 은/는
1. Setting the Topic
Use 은/는 to announce what the sentence is about. It works like saying 'as for...' in English. This is why almost every self-introduction starts with 저는.
저는 한국어를 공부해요.
As for me, I study Korean.
2. Contrast
은/는 quietly implies that the statement is true for this thing, but maybe not for others. It draws a border around the topic.
커피는 좋아해요.
I like coffee (tea, maybe not).
3. General Truths & Known Info
Use 은/는 for definitions, facts, and anything the listener already knows about. Once a thing has been introduced, it becomes the topic.
고래는 포유류예요.
Whales are mammals.
When to Use 이/가
Use 이/가 when you are identifying or introducing the subject rather than commenting on a known topic. It points straight at the noun: this one, not the others. It is also required in several fixed situations — with question words, with 있다/없다, with descriptive verbs, and inside subordinate clauses.
누가 전화했어요?
Who called? (question word)
시간이 없어요.
I don't have time. (with 없다)
날씨가 좋아요.
The weather is nice. (description)
Core Concept
Common Mistakes
How to Choose in 5 Seconds
Follow these 5-second rules.
Frequently Asked Questions
Why is it 제가 and not 저가?
A few pronouns contract before the subject particle 가: 저 → 제가, 나 → 내가, 너 → 네가 (spoken 니가), and 누구 → 누가. With 은/는 there is no contraction, so 저는 and 나는 stay as they are.
Can one sentence use both particles?
Yes, and it's very common. 저는 머리가 아파요 ('as for me, my head hurts') has 저는 as the topic and 머리가 as the subject. Korean often stacks a topic and a subject in the same sentence.
Which one do I use to introduce myself?
Use 은/는: 저는 [name]이에요. Using 제가 would mean 'I am the one who is [name]', which only makes sense if someone was specifically looking for that person.
Why do question words always take 이/가?
Because a question word is asking you to identify something specific out of many options — which is exactly the job of 이/가. You cannot make an unknown thing the 'topic' of a sentence, so 누구는 왔어요? is ungrammatical.
In a story, why does the particle change?
The first mention introduces new information, so it takes 이/가: 옛날에 왕이 살았어요 ('once there lived a king'). After that the king is known, so he becomes the topic: 그 왕은 아주 늙었어요 ('the king was very old').
Is 은/는 the same as the subject of the sentence?
Not necessarily. 은/는 marks the topic, which may or may not be the grammatical subject. In 그 책은 제가 읽었어요 ('as for that book, I read it'), the topic is the book but the subject is 제가.