Three Ways to Say "Because" in Korean
Korean has three main patterns for expressing reasons and causes. Each has specific rules about when it can be used. Mastering the differences between them is essential for natural Korean.
1. N + 때문에 (Because of Noun)
때문에 attaches to nouns and means "because of." It is the simplest reason pattern.
| Structure |
Example |
| Noun + 때문에 |
비 때문에 (because of rain) |
| Noun + 때문에 |
일 때문에 (because of work) |
| Noun + 때문에 |
교통 때문에 (because of traffic) |
With Verbs: V-기 때문에
To use 때문에 with verbs, nominalize the verb first with -기:
| Structure |
Example |
| V-기 때문에 |
바쁘기 때문에 (because of being busy) |
| V-기 때문에 |
비가 오기 때문에 (because it rains) |
Example Sentences
| Korean |
Translation |
| 비 때문에 못 갔어요. |
I couldn't go because of the rain. |
| 일 때문에 바빠요. |
I'm busy because of work. |
| 교통 때문에 늦었어요. |
I was late because of traffic. |
| 시험 때문에 스트레스를 받아요. |
I'm stressed because of the exam. |
| 날씨 때문에 집에 있었어요. |
I stayed home because of the weather. |
N + 때문에 for Blame
때문에 is often used to assign blame or point to a cause:
| Korean |
Translation |
| 너 때문이야! |
It's because of you! |
| 그 사람 때문에 힘들어요. |
It's tough because of that person. |
2. V-아/어서 (Because / So)
-아/어서 connects a reason to its result. It is the most natural, conversational way to give reasons.
| Verb Stem Ending |
Rule |
Example |
| ㅏ or ㅗ |
+ 아서 |
아프다 → 아파서 |
| Other vowels |
+ 어서 |
피곤하다 → 피곤해서 |
| 하다 |
→ 해서 |
공부하다 → 공부해서 |
Example Sentences
| Korean |
Translation |
| 배가 아파서 병원에 갔어요. |
I went to the hospital because my stomach hurt. |
| 날씨가 좋아서 산책했어요. |
I took a walk because the weather was nice. |
| 피곤해서 일찍 잤어요. |
I slept early because I was tired. |
| 시간이 없어서 못 갔어요. |
I couldn't go because I didn't have time. |
| 한국을 좋아해서 한국어를 배워요. |
I learn Korean because I like Korea. |
Rules for -아/어서
- No tense on the first clause: Tense is only marked on the final verb.
| Correct |
Incorrect |
| 아파서 병원에 갔어요. |
아팠어서 병원에 갔어요. |
- Cannot be used before commands or suggestions:
| Incorrect |
Correct Alternative |
| 추워서 문을 닫으세요. (X) |
추우니까 문을 닫으세요. (O) |
| 배가 고파서 먹읍시다. (X) |
배가 고프니까 먹읍시다. (O) |
3. V-(으)니까 (Because / Since)
-(으)니까 is the most versatile reason pattern. It can be used with statements, commands, suggestions, and discoveries.
| Verb Stem Ending |
Rule |
Example |
| Vowel |
+ 니까 |
가다 → 가니까 |
| Consonant |
+ 으니까 |
먹다 → 먹으니까 |
| ㄹ ending |
Drop ㄹ + 니까 |
살다 → 사니까 |
Past Tense: -았/었으니까
Unlike -아/어서, (으)니까 allows past tense on the first clause:
| Present |
Past |
| 피곤하니까 |
피곤했으니까 |
| 바쁘니까 |
바빴으니까 |
Example Sentences
| Korean |
Translation |
| 피곤하니까 일찍 자요. |
Since I'm tired, I'll sleep early. |
| 추우니까 문을 닫으세요. |
Since it's cold, please close the door. |
| 시간이 없으니까 빨리 가자. |
Since we don't have time, let's go quickly. |
| 비가 오니까 우산을 가져가세요. |
Since it's raining, take an umbrella. |
| 맛있으니까 더 드세요. |
Since it's delicious, please eat more. |
Discovery/Realization
-(으)니까 can also express discovering something after doing an action:
| Korean |
Translation |
| 가니까 아무도 없었어요. |
When I went, nobody was there. |
| 먹으니까 맛있었어요. |
When I ate it, it was delicious. |
Comparison Table
| Feature |
때문에 |
-아/어서 |
-(으)니까 |
| Attaches to |
Nouns (V-기 때문에 for verbs) |
Verb stems |
Verb stems |
| Tense on first clause |
O (with -기 때문에) |
X |
O |
| With commands |
O |
X |
O |
| With suggestions |
O |
X |
O |
| Nuance |
"because of" (cause/blame) |
Natural reason |
Reason / discovery |
| Formality |
Neutral to formal |
Casual to polite |
All levels |
When to Use Which?
| Situation |
Best Choice |
Example |
| Blaming something |
때문에 |
비 때문에 못 갔어요. |
| Stating a reason naturally |
-아/어서 |
배가 아파서 쉬었어요. |
| Before commands/suggestions |
-(으)니까 |
추우니까 코트를 입으세요. |
| Formal writing/speeches |
-기 때문에 |
경제가 어렵기 때문에... |
| Discovering something |
-(으)니까 |
해 보니까 쉬웠어요. |
Common Mistakes
| Mistake |
Correction |
Why |
| 추워서 닫으세요. |
추우니까 닫으세요. |
-아/어서 cannot precede commands |
| 아팠어서 병원에 갔어요. |
아파서 병원에 갔어요. |
No past tense before -아/어서 |
| 비 때문에서 |
비 때문에 |
때문에 does not take -서 |
Practice
Choose the correct reason pattern:
- ___ the weather is nice, let's go outside. → 날씨가 좋으니까 밖에 나가자.
- I was late because of traffic. → 교통 때문에 늦었어요.
- I stayed home because I was sick. → 아파서 집에 있었어요.
- Since it's raining, take an umbrella. → 비가 오니까 우산을 가져가세요.