Today, you'll learn how to express the reason using 으니까 grammar. I'll also show you the comparison between 아/어/여서 and 으니까.
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1. 으니까 Grammar
(으)니까 is a connective ending that shows reason or basis. Especially, it is used when a speaker tells the other person the basis for his or her claim or opinion.
You can attach it to a verb, adjective, 이다 and 아니다. You attach (으)니까 to the first clause and make it a reason for the second clause.
The first part 아기가 자요(the baby is sleeping) is the reason for the second part 조용히 하세요(please be quiet).
오늘은 바빠요. (Today I'm busy.) + 내일 이야기 해요. (Let's talk tomorrow.)
→ 오늘은 바쁘니까 내일 이야기해요. I'm busy today, let's talk tomorrow.
The first part "바쁘다" is the reason for the second part. So, we attach (으)니까 grammar. You can translate it as "because," "so," or "since" as well.
This ending is often used as the reason for a command or request to do something together.
지금 바쁘니까 내일 이야기해요. Let's talk tomorrow, I'm busy now.
늦었으니까 내일 가세요. It's late, so go tomorrow.
2. Conjugation Information
The rule (으)니까 has two forms, 으니까 and 니까. The final consonant of the stem is the key to conjugation.
Regular Rules
(으)니까 | Example | |
받침 O | +으니까 | 먹다(to eat) → 먹으니까 |
받침 X | +니까 | 마시다(to drink) → 마시니까 |
ㄹ 받침 | Drop ㄹ + 니까 | 놀다(to play) → 노니까 |
Let's see some more examples.
입다 (to wear) → 입으니까
앉다 (to sit) → 앉으니까
가다 (to go) → 가니까
쓰다 (to write) → 쓰니까
공부하다 (to study) → 공부하니까
살다 (to live) → 사니까
만들다 (to make) → 만드니까
Irregular Rules
(으)니까 | Example | |
받침 ㄷ | ㄷ→ㄹ + 으니까 | 듣다(to listen) → 들으니까 |
받침 ㅅ | Erase ㅅ + 으니까 | 잇다(to connect) → 이으니까 |
받침 ㅂ | Erase ㅂ + 우니까 | 돕다(to help) → 도우니까 |
받침 ㅎ | Erase ㅎ +니까 | 파랗다 (to be blue) → 파라니까 |
걷다 (to walk) → 걸으니까
묻다 (to ask) → 물으니까
긋다 (to draw lines) → 그으니까
짓다 (to build) → 지으니까
줍다 (to pick up) → 주우니까
굽다 (to bake/to roast) → 구우니까
노랗다 (to be yellow) → 노라니까
동그랗다 (to be round) → 동그라니
Past Tense
You can talk about past events as a reason. In that case, you can use 았/었/였+으니까. You'll always need 으니까 because the past tense word 았/었/였 has the final consonant!
먹다 (to eat) → 먹었으니까
마시다 (to drink) → 마셨으니까
놀다 (to play) → 놀았으니까
공부하다 (to study) → 공부했으니까
듣다 (to listen) → 들었으니까
잇다 (to connect) → 이었으니까
돕다 (to help) → 도왔으니까
파랗다 (to be blue) → 파랬으니까
3. Sentence Information
Form
① To emphasize meaning, people use 으니까+는 form, 으니까는 or 으니깐.
Let's go tomorrow since it rains.
= 비가 오니까 내일 갑시다.
= 비가 오니까는 내일 갑시다.
= 비가 오니깐 내일 갑시다.
② There is a short form as well. Instead of 으니까, you can say 으니.
비가 오니까 내일 갑시다.
= 비가 오니 내일 갑시다.
Comparison
Let's compare the 아/어/여서 with (으)니까. They can both be used to explain the reason.
아/어/여서 | (으)니까 |
You simply explain your reason. | You show a reason for your opinion or claim. |
You can't use it as a command or propositive. | You can use it as a command or suggest doing something together. |
(X) 비가 와서 내일 가세요. | 비가 오니까 내일 가세요. Go tomorrow, it's rainy. |
You can't attach the past tense words 았/었/였. | You can attach the past tense word 았/었/였. |
(X) 비가 왔어서 산에 안 갔어요. | 비가 왔으니까 산에 가지 마세요. It rained so don't go to the mountain. |
It is often used in idiomatic expressions. | It's not used in idiomatic expressions. |
만나서 반갑습니다. Nice to meet you. | (X) 만나니까 반갑습니다. |
4. Examples
1
눈이 오니까 조심히 오세요.
It's snowy so please come carefully.
눈이 오다(to be snowy) + 조심히 오다 (to come carefully)
If you want to learn more about weather in Korean, please click here.
2
젠 씨는 열심히 공부했으니까 시험을 잘 볼 거예요.
Jen studied hard, so she will do well in the test.
열심히 공부하다 (to study hard) + 시험을 잘 보다(to take a test well)
3
이번 달은 돈을 많이 썼으니까 이제 돈을 아껴 써요.
We spent a lot of money this month, so let's conserve money from now on.
이번 달-this month, 돈-money, 많이-a lot, 쓰다-to spend, 아껴 쓰다-conserve
4
지금은 피곤하니까 내일 도와줄게요.
I'll help you tomorrow, I'm tired now.
지금-now, 피곤하다-to be tired, 내일-tomorrow, 도와주다-to give help
5
이 드라마 진짜 재밌으니까 나중에 꼭 보세요.
This show is really fun, you must watch it later.
드라마-drama, show, 진짜-really, 재밌다-to be fun/funny, 나중에-later, 꼭-must, 보다-watch
5. Wrap-up & Worksheet
Today, you learned how to say "because," "so," or "since" in Korean.
으니까 can be attached verbs, adjectives, 이다, and 아니다.
It shows the reason of your opinion or claim.
You can talk about the past event as a reason as well.
Here, I prepared the free and printable worksheet. The answers are throughout the lesson. So, once you finished solving, come back to the lesson and check your answers. It'll help you to review as well!
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