-을걸

V/Adj/이다,아니다 + 을걸(요)? 1. It expresses a guess or assumption with quite strong conviction. It is mainly used in casual spoken situations between close people. (I bet~, I guess~)

수지 남자친구 있을걸?

I bet Suzy has a boyfriend?

지금 밥 안 먹으면 나중에 배고플걸?

If you don't eat now, I bet you'll be hungry later?

태형 씨 지금 안 잘걸요?

I bet Taehyung isn't sleeping right now?

• Even when you add -요 , it still feels like you are talking to a familiar adult. If you want to express your guess in a more formal or polite way, use the “-을 것 같다” pattern.

교수님, 저 늦을걸요 X

교수님, 저 늦을 것 같습니다. O Professor, I think I'll be late.

V + 을걸 2. It is always used with the subject "I" in casual form, expressing regret to oneself. (I should have~) (For the "You should have~" meaning, see meaning 2 on the ‘-지’ page.)

사람 많네, 일찍 올걸.

It's crowded, I should have come earlier.

어렸을 때 공부 좀 많이 할걸.

I should have studied harder when I was young.

아, 그 주식 사지 말걸.

Ah, I should not have bought that stock.

→ “I should not have~” expression is said with ‘~지 말걸’.

• It is often used with expressions like ‘그랬다’, ‘그랬네’, ‘그랬어요’…

주식 살걸 그랬다.

공부 더 많이 할걸 그랬네.

Especially, when speaking to someone older, we don’t use ‘-걸요’ to express regret. Instead, we use -걸 그랬어요.

A: 토니 씨 시험 잘 쳤어요?

B: 아니요… 공부 더 할걸 그랬어요.

• Simply, adding the past tense of ‘~어야 되다/하다(should)’ can also express regret. The difference is that the ‘~어야 됐다/했다’ can be connected with other endings, while -을걸 is a sentence-ending form.

운동을 많이 해야 됐어요.

→ 운동을 많이 해야 됐는데 바빠서 못했어요.

• Tense: 었O, 겠X

수지 밥 먹었을걸 O

수지 밥 먹겠을걸 X → 수지 밥 먹을걸(it already contains future tense.)