Beginner Estimated read: 3 mins

-아/어서 (Reason)

Used to express the reason or cause for the action/state in the following clause. It connects a reason with a result.

Summary

Equivalent

Because / So

Also: -(으)니까 (Because/Since)

Example

I had a stomachache, so I went to the hospital.

배가 아파서 병원에 갔어요.

Grammar rules

  • Use '-아서' for stems with ㅏ or ㅗ.
  • Use '-어서' for all other vowels.
  • Use '해서' for '하다' verbs.
  • Do NOT conjugate into past or future tense before '-아/어서'.
  • The final verb determines the tense of the sentence.
  • Cannot be used with imperative sentences (-(으)세요, -아/어라) or propositive sentences (-(으)ㅂ시다, -(으)ㄹ까요). Also, tense markers (-았/었-, -겠-) cannot proceed '-아/어서'.

    비가 와서 집에 있었어요. (O) | 비가 왔어서 집에 있었어요. (X) | 비가 와서 우산을 쓰세요. (X -> 우산을 쓰세요 requires -(으)니까)

Patterns

1

Verbs/Adjectives with 'ㅏ' or 'ㅗ'

Present · Stem + 아서

2

Verbs/Adjectives with other vowels

Present · Stem + 어서

3

하다 Verbs/Adjectives

Present · 해서

Example sentences

Verbs/Adjectives with 'ㅏ' or 'ㅗ' · Present · Stem + 아서

I had a stomachache, so I went to the hospital.

배가 아파서 병원에 갔어요.

Verbs/Adjectives with other vowels · Present · Stem + 어서

I'm sorry for being late.

늦어서 죄송합니다.

하다 Verbs/Adjectives · Present · 해서

Because the weather was hot, I ate ice cream.

날씨가 더워서 아이스크림을 먹었어요.

Conversation

A: Why didn't you come to school yesterday?

왜 어제 학교에 안 왔어요?

B: I couldn't come because I caught a cold.

감기에 걸려서 못 왔어요.

Practice

Fill in the blank

Select the correct form indicating reason.

Eating.

Busy.