-(으)니까
So, Because
-니까 is a connective ending that means 'because' or 'so'. It links a reason in the first clause to a result, command, or suggestion in the second clause.
How It Works
-니까 is a crucial grammar pattern for expressing reasons, especially when leading to commands or suggestions. It's more versatile than -아/어서 in these situations.
Conjugation Rules:
1. Verb/Adjective stem ends in a vowel or ㄹ: Add -니까.
- 가다 (to go) → 가니까 (because I go)
- 예쁘다 (to be pretty) → 예쁘니까 (because it's pretty)
- 만들다 (to make) → 만드니까 (because I make) (Note: ㄹ is dropped)
2. Verb/Adjective stem ends in a consonant (except ㄹ): Add -으니까.
- 먹다 (to eat) → 먹으니까 (because I eat)
- 좋다 (to be good) → 좋으니까 (because it's good)
3. Nouns: Add -(이)니까.
- 학생 (student) → 학생이니까 (because I'm a student)
- 주말 (weekend) → 주말이니까 (because it's the weekend)
Key Usages:
1. Reason for a Command or Suggestion
This is the most important function of -니까 and its main difference from -아/어서. The second clause is often a command (-으세요), a suggestion (-ㄹ까요?), or a proposal (-ㅂ시다).
• 날씨가 추우니까 옷을 따뜻하게 입으세요. (Because the weather is cold, please dress warmly.)
• 이 영화가 재미있으니까 같이 봐요. (Because this movie is fun, let's watch it together.)
2. Reason based on Speaker's Discovery
-니까 can be used when the speaker realizes something and then states the result. It often translates to 'When I did X, I found that Y, so...'.
• 집에 와 보니까 아무도 없었어요. (When I came home, I found that nobody was there.)
3. Use with Tense
Unlike -아/어서, -니까 can be attached to the past tense marker -았/었-.
• 어제 시험이 끝났으니까 오늘은 놀러 가자. (Because the exam finished yesterday, let's go hang out today.)
Examples (5)
- 날씨가 더우니까 에어컨을 켤까요?
Since it's hot, shall we turn on the air conditioner?
Word by Word: Weather hot-because air conditioner shall turn on?
The reason (it's hot) is followed by a suggestion (shall we turn on the AC?).
- 지금은 바쁘니까 나중에 전화해 주세요.
I'm busy right now, so please call me later.
Word by Word: Now busy-because later call please give.
The reason (I'm busy) is followed by a command/request (please call later).
- 어제 숙제를 다 했으니까 오늘은 마음이 편해요.
Because I finished all my homework yesterday, I feel at ease today.
Word by Word: Yesterday homework all did-because today mind is comfortable.
This example shows -니까 used with the past tense marker -했-. Unlike -아/어서, -니까 can take a past tense marker, and then it often sounds like you are explaining your reason.
- 저는 외국인이니까 한국말을 잘 못해요.
Because I am a foreigner, I don't speak Korean well.
Word by Word: I foreigner-because Korean language well cannot do.
Here, -이니까 is attached to a noun (외국인) to state a reason.
- 창문을 여니까 시원한 바람이 들어왔어요.
When I opened the window, a cool breeze came in.
Word by Word: Window open-so cool breeze came in.
This shows the 'discovery' nuance. The action of opening the window led to the discovery/result of a cool breeze.
Common Mistakes
Using -아/어서 with commands or suggestions.
Not Quite날씨가 좋아서 공원에 갑시다.Better날씨가 좋으니까 공원에 갑시다.The grammar pattern -아/어서 cannot be followed by propositive sentences (let's do...) or imperative sentences (please do...). You must use -니까 in these cases.
Using the past tense marker -았/었- before -아/어서.
Not Quite어제 피곤했어서 일찍 잤어요.Better어제 피곤해서 일찍 잤어요.You cannot attach the past tense marker directly to -아/어서. The tense is understood from the final verb.
Learn This First
To express 'so/because', you need to understand verb conjugation.
Related Patterns
- -아/어서Because of, Therefore
Both mean 'because', but -아/어서 is used for general, direct cause-and-effect and cannot be used with commands or suggestions. -니까 is used when the reason leads to a command, suggestion, or is a subjective judgment.
- -기 때문에Because
Another pattern for 'because'. -기 때문에 is more formal and emphasizes a logical, objective reason. Like -아/어서, it is normally not used with commands or suggestions; use -니까 for those.
- -ㄴ/는데Background Info, But
While -ㄴ/는데 can provide background information that functions like a reason, it's much softer and more indirect than -니까. It sets a scene or context rather than stating a direct cause.
- -더니I Noticed, And Then
Similar to the 'discovery' nuance of -니까. -더니 is used when the speaker observes something (first clause) and then reports the resulting change or situation (second clause).
Learn Next
Patterns that build on this one.