~(으)니까: How to Say "Because" in Korean

In the previous post, you learned that ~아/어서 can mean "because" - but that it can't be followed by commands or suggestions.

So what do you use when you want to say "because it's raining, bring an umbrella"?

~(으)니까.

~(으)니까 is the second major "because" connector in Korean - and it's the one to reach for when you're giving advice, making requests, or offering a reason for something you want someone to do. This post covers everything you need to know - including the critical differences between ~아/어서 and ~(으)니까.

What Does ~(으)니까 Mean?

~(으)니까 means "because," "since," or "so" - expressing the reason or basis for the statement that follows.

비가 오니까 우산을 가져오세요. Because it's raining, bring an umbrella.

배가 고프니까 빨리 먹읍시다. Since I'm hungry, let's eat quickly.

How to Form ~(으)니까

💡 ㄹ stems drop ㄹ before 니까 - same pattern as ~(으)시- and ~ㅂ니다: 알다 → 아니까 / 만들다 → 만드니까

Conjugation Table

~(으)니까 in Real Sentences

With commands (-(으)세요)

This is where ~(으)니까 really shines - ~아/어서 cannot do this, but ~(으)니까 can:

추우니까 따뜻하게 입으세요.

• Natural: Because it's cold, dress warmly.

늦으니까 빨리 오세요.

• Natural: Because you're late, please come quickly.

여기가 조용하니까 여기에서 공부하세요.

• Natural: Since it's quiet here, study here.

피곤하니까 오늘은 쉬세요.

• Natural: Since you're tired, rest today.

길이 막히니까 지하철을 타세요.

• Natural: Because the roads are congested, take the subway.

With suggestions (-(으)ㄹ까요 / -(으)ㅂ시다)

배고프니까 밥 먹을까요?

• Natural: Since we're hungry, shall we eat?

날씨가 좋으니까 산책할까요?

• Natural: Since the weather is nice, shall we take a walk?

늦었으니까 택시를 탑시다.

• Natural: Since it's late, let's take a taxi.

내일 시험이 있으니까 오늘 공부합시다.

• Natural: Since there's an exam tomorrow, let's study today.

Giving reasons for statements

한국어가 어려우니까 매일 연습해야 해요.

• Natural: Because Korean is difficult, you need to practice every day.

그 식당은 맛있으니까 꼭 가 보세요.

• Natural: Because that restaurant is delicious, you should definitely go.

시간이 없으니까 빨리 결정해요.

• Natural: Since there's no time, let's decide quickly.

✅ Key Advantage of ~(으)니까: Tense is Allowed

Unlike ~아/어서, ~(으)니까 can take past tense in the first clause:

~아/어서 vs ~(으)니까 - The Full Comparison

This is the core distinction every learner needs:

Quick rule of thumb:

• Need a command or suggestion after? → ~(으)니까
• Connecting two facts naturally? → ~아/어서 or ~(으)니까 both work
• Sequential action? → ~아/어서 only

Same Sentence, Two Connectors

Let's see the difference in practice:

With ~아/어서 (natural facts):

비가 와서 집에 있었어요. (It was raining, so I stayed home.)

With ~(으)니까 (reason for suggestion):

비가 오니까 집에 있으세요. (Because it's raining, stay home.)

With ~아/어서:

배가 고파서 밥을 먹었어요. (I was hungry, so I ate.)

With ~(으)니까:

배가 고프니까 빨리 먹읍시다. (Since we're hungry, let's eat quickly.)

~(으)니까 for Self-Reasoning

~(으)니까 is also used when you're explaining your own reasoning or conclusion - giving a logical basis for what follows:

제가 직접 만들었으니까 맛있을 거예요.

• Natural: Since I made it myself, it'll be delicious.

제가 틀렸으니까 사과할게요.

• Natural: Since I was wrong, I'll apologize.

이미 결정했으니까 후회하지 마세요.

• Natural: Since it's already decided, don't regret it.

Real Conversations Using ~(으)니까

📍 Conversation 1: Giving advice

A: 요즘 너무 피곤해요. (I've been so tired lately.)

B: 그러면 오늘은 일찍 자세요. 내일 일이 많으니까 푹 쉬어야 해요. (Then go to bed early today. Since there's a lot to do tomorrow, you need to rest well.)

A: 맞아요. 요즘 너무 무리했으니까 좀 쉬어야겠어요. (You're right. Since I've been overdoing it lately, I should rest a bit.)

📍 Conversation 2: Making a suggestion

A: 점심 뭐 먹을까요? (What shall we eat for lunch?)

B: 오늘 날씨가 추우니까 따뜻한 거 먹을까요? (Since the weather is cold today, shall we eat something warm?)

A: 좋아요! 근처에 김치찌개 맛있는 집이 있으니까 거기 갑시다. (Sounds good! Since there's a place nearby with good kimchi jjigae, let's go there.)

📍 Conversation 3: Explaining a decision

A: 왜 이 코스를 선택했어요? (Why did you choose this course?)

B: 체계적으로 배우고 싶었으니까요. 혼자 공부하면 어디서부터 시작해야 할지 모르니까요. (Because I wanted to learn systematically. Because when studying alone, I don't know where to start.)

A: 맞아요. 기초가 중요하니까 잘 선택했어요. (Right. Since the foundation is important, you chose well.)

Common Mistakes to Avoid

❌ Mistake 1: Using ~아/어서 before commands

❌ 추워서 따뜻하게 입으세요. ✅ 추우니까 따뜻하게 입으세요.

❌ Mistake 2: ㄹ irregular — ㄹ drops before ~(으)니까

❌ 알으니까 ✅ 아니까 (알다 → ㄹ drops)

❌ 만들으니까 ✅ 만드니까 (만들다 → ㄹ drops)

❌ Mistake 3: Using ~(으)니까 for sequential actions

❌ 집에 가니까 쉬었어요. ✅ 집에 가서 쉬었어요. (sequence → ~아/어서)

Quick Practice

Fill in the blank with ~아/어서 or ~(으)니까:

1. 날씨가 좋_____ 산책합시다. (suggestion)
2. 배가 고_____ 밥을 먹었어요. (natural result)
3. 늦_____ 빨리 오세요. (command)
4. 마트에 _____ 과일을 샀어요. (sequence)
5. 이미 봤_____ 다른 걸 볼까요? (past tense + suggestion)

Answers:

1. 날씨가 좋으니까 산책합시다.
2. 배가 고파서 밥을 먹었어요.
3. 늦으니까 빨리 오세요.
4. 마트에 가서 과일을 샀어요.
5. 이미 봤으니까 다른 걸 볼까요?

Summary

~(으)니까 and ~아/어서 are partners - each covering what the other can't. Together, they handle almost every "because" situation in Korean. Learn both, and your sentences will connect as naturally as a native speaker's.