이 vs 가 (i vs ga): why it's 제가, not 저가

A particle is a small word ending that shows the role of a word in the sentence. The subject is the person or thing that does the action, or is in a state.

You probably know 제가 (jega) — "I" — and 비가 와요 (biga wayo) — "It's raining." You used them before you knew what the small 가 does.

How do I choose 이 or 가?

It works like 은/는. Look at the last block. Does it have a 받침 (batchim)? A 받침 is a consonant at the bottom of the block.

• Ends in a consonant → 이
• Ends in a vowel → 가

Why is it 제가, not 저가?

Some very common words don't just add 가. They change their form.

So you say 제가 할게요 [제가 할께요] (jega halgeyo) — "I'll do it." Never say 저가 할게요.

There is one more thing about speech. Most Koreans today say ㅐ and ㅔ the same way. So 내가 ("I") and 네가 ("you") sound the same. To make them different, people often say 네가 as 니가 in casual speech. It is not the standard form, but you will hear it very often.

이/가 points at "this one"

은/는 shows the topic. 이/가 points at this one: the new information, the important thing right now.

In English, "I" is often the subject. In Korean, the body part or the thing is often the subject.

A short scene: someone ate the last rice cake in the office snack box.

• A: 누가 먹었어요? ("Who ate it?")
• B: …제가요. ("…It was me.")

The answer also uses 이/가. It is the same with food: 뭐가 맛있어요? ("What is good here?") → 김치찌개가 맛있어요 ("The kimchi stew is good").

What are 이게 and 그게?

"This thing" and "that thing" are 이것, 그것 and 저것. When you add 이, people make them shorter in speech.

So the common shop question 이게 뭐예요? (ige mwoyeyo?) — "What is this?" — comes from 이것이 무엇이에요. People shorten it in real speech.

Easy mistakes

• 저가, 나가, 누구가 are wrong. Use 제가, 내가, 누가.
• 시간을 있어요 is wrong. 있다 and 없다 use 이/가: 시간이 있어요.
• 책가, 사람가 are wrong. These words end in a consonant, so use 책이, 사람이.
• 돈을 필요해요 is wrong. 필요하다 ("to be needed") uses 이/가: 돈이 필요해요.

Why does Korean say "my stomach is hungry"?

Korean often describes a feeling or state as something that happens to a thing. So the thing becomes the subject.

• 머리가 아파요 (meoriga apayo) — "My head hurts." The head is the subject.
• 이게 좋아요 [이게 조아요] (ige joayo) — "I like this one." Word for word: "This is good (to me)."
• 돈이 필요해요 [도니 피료해요] (doni piryohaeyo) — "I need money." Word for word: "Money is needed."

Now 있어요 is easy to understand too. 시간이 있어요 means "time exists". Time is not an object here, so there is no 을/를.

How does this work with 은/는? Compare these two. 누가 했어요? ("Who did it?") → 민수가 했어요 ("Minsu did it"). And 민수는 회사원이에요 ("As for Minsu, he is an office worker").

Our guide to 은 vs 는 explains the other half of this.

Quick check

1. ___ 할게요. (I'll do it, polite.) → 제가
2. 우산___ 없어요. (I don't have an umbrella.) → 산 ends in ㄴ: 우산이
3. ___ 뭐예요? (What is this?) → 이게