-더니
used to be… and now; did that… and so
Reports something you witnessed earlier, then what followed from it. The subject is someone else — for your own actions, the form changes to -았/었더니.
Build it
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When to use it
Attach -더니 to any stem — no vowel rule, ㄹ stays, no tense in front for the basic use.
Like -더라고요, the 더 element means you observed it yourself. So the subject is normally someone or something else, not you.
Two readings share the form. Contrast: the situation has since changed — 아까는 춥더니 지금은 따뜻하네요. Consequence: what you saw led to what followed — 열심히 공부하더니 시험에 합격했어요.
In the consequence reading there is often a hint of “as you’d expect” — the outcome makes sense given what you had observed.
How to attach it
| Situation | Form | Example |
|---|---|---|
| Any verb or adjective | -더니 | 춥다 → 춥더니 |
| ㄹ stems keep the ㄹ | -더니 | 만들다 → 만들더니 |
| Contrast | then vs now | 아까는 춥더니 지금은 따뜻해요 |
| Consequence | observed cause | 열심히 하더니 합격했어요 |
| Subject | someone else | 제가 공부하더니 is wrong |
| Your own action | -았/었더니 | 제가 갔더니 |
In use
아까는 춥더니 지금은 따뜻하네요.
It was cold earlier, and now it’s warm.
동생이 열심히 공부하더니 시험에 합격했어요.
My brother studied hard, and sure enough he passed.
그 가게가 잘되더니 지점을 냈어요.
That shop was doing well, and now they’ve opened a branch.
아이가 계속 울더니 잠이 들었어요.
The child cried and cried, and then fell asleep.
친구가 매일 요리를 만들더니 실력이 늘었어요.
My friend cooked every day, and her skills improved.
어제는 비가 오더니 오늘은 맑네요.
It rained yesterday, and today it’s clear.
Compared with
-았/었더니
The subject decides which you use. -더니 reports what you saw someone else do; -았/었더니 reports what you did yourself and what you then found.
동생이 공부하더니 합격했어요. (I watched him) / 제가 갔더니 아무도 없었어요. (I went and found)
-지만
In the contrast reading, -지만 states a plain opposition while -더니 adds that you witnessed the earlier state and the change surprised you.
아까는 추웠지만 지금은 따뜻해요. (plain) / 아까는 춥더니 지금은 따뜻하네요. (I noticed the change)
-더라고요
The same 더 element. Both require first-hand observation, which is why neither works comfortably about your own inner states.
춥더라고요. (I found it cold) / 춥더니 따뜻해졌어요. (it was cold, then warmed up)
Watch out
제가 열심히 공부하더니 합격했어요.
제가 열심히 공부했더니 합격했어요.
-더니 reports what you observed in someone else. For your own action, use -았/었더니.
친구가 요리를 만드더니 실력이 늘었어요.
친구가 요리를 만들더니 실력이 늘었어요.
-더니 attaches to the plain stem and ㄹ stays, unlike -는 where it drops.
뉴스에서 봤는데 그 가게가 잘되더니 지점을 냈대요.
그 가게가 잘된다더니 지점을 냈대요.
-더니 claims you saw it yourself. For something you only heard about, build it on the reported form instead.
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