🎵 Start with this song!
“이렇게 쉽게 니가 날 떠날 줄 몰랐어…”
Have you ever been completely caught off guard by something — and didn’t know how to express it in Korean?
This grammar point is exactly what you need. 😊
1. What is -(으)ㄹ 줄 몰랐어요?
-(으)ㄹ 줄 몰랐어요 is used in two ways:
- ① Simply not knowing a fact — neutral, no drama
- ② Being surprised by something unexpected — “I had no idea!”
We’ll look at both uses in detail below!
2. Use ①: Simply not knowing a fact
This is the more neutral use. You just genuinely didn’t know something — no big surprise, no emotional reaction.
네가 선생님인 줄 몰랐어요.
I didn’t know you were a teacher.
오늘 휴일인 줄 몰랐어요.
I didn’t know today was a holiday.
그 카페가 문을 닫을 줄 몰랐어요.
I didn’t know that café was closing.
한국어에 이런 표현이 있을 줄 몰랐어요.
I didn’t know Korean had an expression like this.
💡 This use often appears with nouns + 인 줄 몰랐어요 when stating an unknown fact about what something is.
3. Use ②: Surprise at something unexpected
Here, the feeling is stronger — you expected one thing, but reality was completely different. That gap between expectation and reality is what makes this use so expressive!
이렇게 어려울 줄 몰랐어요.
I had no idea it would be this hard.
네가 올 줄 몰랐어요.
I had no idea you would come.
한국어가 이렇게 재미있을 줄 몰랐어요!
I never thought Korean would be this fun!
💡 How to tell the two uses apart?
Context and tone do the work:
- With 이렇게 / 그렇게 → usually expressing surprise
- Without them, in a neutral tone → simply stating you didn’t know a fact
4. How to conjugate
| Stem ending | Rule | Example |
|---|---|---|
| Vowel | + ㄹ 줄 몰랐어요 | 오다 → 올 줄 몰랐어요 |
| Consonant | + 을 줄 몰랐어요 | 먹다 → 먹을 줄 몰랐어요 |
| ㄹ stem | + 줄 몰랐어요 | 알다 → 알 줄 몰랐어요 |
비가 이렇게 많이 올 줄 몰랐어요.
I had no idea it would rain this much.
그 식당이 이렇게 맛있을 줄 몰랐어요.
I had no idea that restaurant would be so delicious.
5. The opposite: -(으)ㄹ 줄 알았어요
If you want to say you expected something (but were wrong), use -(으)ㄹ 줄 알았어요.-(으)ㄹ 줄 알았어요=”I thought that… (but I was wrong)”
시험이 쉬울 줄 알았어요.
I thought the exam would be easy. (but it wasn’t!)
네가 안 올 줄 알았어요.
I thought you wouldn’t come. (but you did!)
💡 Both patterns express a wrong assumption — just from opposite directions:
| Pattern | Meaning | Feeling |
|---|---|---|
| -(으)ㄹ 줄 몰랐어요 | “I didn’t know it would…” | Surprise — I never expected this! |
| -(으)ㄹ 줄 알았어요 | “I thought it would…” | I assumed something — but I was wrong. |
6. Adding emphasis with 이렇게 & 그렇게
In natural speech, Koreans often add 이렇게 (like this / this much) or 그렇게 (like that / that much) to make the surprise feel more vivid.
이렇게 좋을 줄 몰랐어요.
I had no idea it would be this good.
그 사람이 그렇게 유명할 줄 몰랐어요.
I had no idea that person was so famous.
한국 드라마가 이렇게 재미있을 줄 몰랐어요!
I never knew Korean dramas could be this fun!
7. In the past: what you didn’t know had happened
To talk about not knowing that something already happened, use the past form -았/었을 줄 몰랐어요.-았/었을 줄 몰랐어요=”I had no idea that [it] had already…”
네가 이미 갔을 줄 몰랐어요.
I had no idea you had already left.
그 영화가 그렇게 슬펐을 줄 몰랐어요.
I had no idea the movie was that sad.
이미 끝났을 줄 몰랐어요.
I didn’t realize it had already ended.
⚠️ Watch out!
- ❌ 네가 갈 줄 몰랐어요. (talking about a past event that already happened)
- ✅ 네가 갔을 줄 몰랐어요. (correct — using the past form)
8. Real-life examples 🗣️
A: 오늘 파티 어땠어요?
B: 너무 좋았어요! 이렇게 재미있을 줄 몰랐어요.
A: How was the party today? B: It was amazing! I had no idea it would be this fun.
A: 왜 우산 안 가져왔어요?
B: 비가 올 줄 몰랐어요!
A: Why didn’t you bring an umbrella? B: I had no idea it was going to rain!
한국에 오기 전에 김치를 이렇게 좋아하게 될 줄 몰랐어요.
Before coming to Korea, I never knew I’d fall in love with kimchi like this.
9. Full summary
| Pattern | Meaning | Example |
|---|---|---|
| -(으)ㄹ 줄 몰랐어요 ① | I didn’t know (a fact) | 오늘 휴일인 줄 몰랐어요. |
| -(으)ㄹ 줄 몰랐어요 ② | I had no idea it would… | 이렇게 어려울 줄 몰랐어요. |
| -(으)ㄹ 줄 알았어요 | I thought it would… (but wrong) | 쉬울 줄 알았어요. |
| -았/었을 줄 몰랐어요 | I had no idea it had already… | 이미 끝났을 줄 몰랐어요. |
🎵 [Lalla Challenge!]
Think about something that surprised you recently — in Korean learning or in life! ✨
Write a sentence using -(으)ㄹ 줄 몰랐어요:
한국어 문법이 이렇게 _____ 줄 몰랐어요! 💭
Drop your sentence in the comments! 👇
Happy learning with Lalla Korean! 🌸
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