-더니 expresses a sequence where the speaker observed the first action/state, and then a result or change occurred. It means "I saw/noticed [A], and then [B]" with emphasis on the speaker's direct observation.
Structure
Verb/Adjective stem + -더니
Breakdown:
- -더-: Past observation marker (retrospective)
- -니: Connective showing result/consequence
Literal meaning: "[I observed that]..., and then..."
Formation Rules
All Verbs and Adjectives: -더니
Uniform attachment:
- 가다 → 가더니 (went, and then...)
- 먹다 → 먹더니 (was eating, and then...)
- 좋다 → 좋더니 (was good, and then...)
- 아프다 → 아프더니 (was sick, and then...)
- 공부하다 → 공부하더니 (was studying, and then...)
ㄹ Irregular: Keep ㄹ + -더니
No dropping of ㄹ:
- 살다 → 살더니 (was living, and then...)
- 만들다 → 만들더니 (was making, and then...)
- 팔다 → 팔더니 (was selling, and then...)
하다 Verbs: -하더니
All 하다 verbs:
- 일하다 → 일하더니 (was working, and then...)
- 운동하다 → 운동하더니 (was exercising, and then...)
- 청소하다 → 청소하더니 (was cleaning, and then...)
Core Meaning: Observed Sequence
Direct Observation → Result
Speaker witnessed the first action:
- 비가 오더니 그쳤어요 (It was raining, and then it stopped)
- 아이가 울더니 잤어요 (The child was crying, and then fell asleep)
- 춥더니 눈이 왔어요 (It was cold, and then it snowed)
Cannot Use for Speaker's Own Actions
❌ Incorrect for first person:
- ❌ 제가 먹더니 배불러요 (I was eating, and then got full)
- ✅ 제가 먹었더니 배불러요 (When I ate, I got full) - use -았/었더니
✅ Correct for observed others:
- 친구가 먹더니 배불러 해요 (My friend was eating, and then seemed full)
Time Gap Between Actions
Indicates passage of time:
- 아침에 아프더니 지금은 괜찮아요 (Was sick this morning, but is okay now)
- 어제 말하더니 오늘 했어요 (Said it yesterday, and did it today)
Common Usage Patterns
Cause and Effect
Observed cause → observed result:
- 열심히 공부하더니 합격했어요 (Was studying hard, and then passed)
- 많이 먹더니 배탈 났어요 (Was eating a lot, and then got a stomachache)
- 피곤하더니 일찍 잤어요 (Was tired, and then went to bed early)
Weather Changes
Observed weather → change:
- 흐리더니 비가 왔어요 (It was cloudy, and then it rained)
- 춥더니 따뜻해졌어요 (It was cold, and then got warm)
- 바람이 불더니 날씨가 좋아졌어요 (Wind was blowing, and then the weather got better)
Behavioral Observations
Noticed behavior → outcome:
- 아이가 안 먹더니 아팠어요 (The child wasn't eating, and then got sick)
- 우울하더니 혼자 있어요 (Was depressed, and then is alone)
- 화나더니 나갔어요 (Was angry, and then left)
Special Form: -았/었더니
Speaker's First Person Experience
For speaker's own actions:
- 제가 먹었더니 배불러요 (When I ate, I got full)
- 운동했더니 건강해졌어요 (When I exercised, I became healthy)
- 공부했더니 시험을 잘 봤어요 (When I studied, I did well on the exam)
Formation: Stem + -았/었더니
- 가다 → 갔더니 (when I went, then...)
- 먹다 → 먹었더니 (when I ate, then...)
- 하다 → 했더니 (when I did, then...)
Discovery Through Action
Did something and discovered result:
- 문을 열었더니 고양이가 있었어요 (When I opened the door, there was a cat)
- 전화했더니 안 받았어요 (When I called, they didn't answer)
- 가 봤더니 문이 닫혀 있었어요 (When I went to see, the door was closed)
Common Expressions
Daily Observations
- 비가 오더니 (it was raining, and then...)
- 춥더니 (it was cold, and then...)
- 아프더니 (was sick, and then...)
- 피곤하더니 (was tired, and then...)
Behavioral Changes
- 화나더니 (was angry, and then...)
- 웃더니 (was laughing, and then...)
- 울더니 (was crying, and then...)
- 말하더니 (was talking, and then...)
First Person Experiences (-았/었더니)
- 먹었더니 (when I ate, then...)
- 갔더니 (when I went, then...)
- 해 봤더니 (when I tried, then...)
- 물어봤더니 (when I asked, then...)
Politeness Levels
Formal (합니다체)
- 비가 오더니 그쳤습니다 (It was raining, and then it stopped)
- 공부하더니 합격했습니다 (Was studying, and then passed)
Polite (해요체)
- 비가 오더니 그쳤어요 (It was raining, and then it stopped)
- 아프더니 나았어요 (Was sick, and then got better)
Casual (반말)
- 비가 오더니 그쳤어 (It was raining, and then stopped)
- 먹더니 갔어 (Was eating, and then left)
Negative Forms
Negative First Clause
안 + Verb + -더니:
- 안 먹더니 배고파했어요 (Wasn't eating, and then was hungry)
- 안 오더니 전화했어요 (Wasn't coming, and then called)
Verb + -지 않더니:
- 먹지 않더니 아팠어요 (Wasn't eating, and then got sick)
- 오지 않더니 취소했어요 (Wasn't coming, and then cancelled)
Can't/Unable
못 + Verb + -더니:
- 못 먹더니 아팠어요 (Couldn't eat, and then got sick)
- 못 자더니 피곤해했어요 (Couldn't sleep, and then was tired)
-더니 vs Similar Patterns
-더니 vs -았/었더니
-더니: Observed others' actions
- 친구가 먹더니 갔어요 (My friend was eating, and then left)
-았/었더니: Speaker's own actions/discoveries
- 제가 먹었더니 배불러요 (When I ate, I got full)
-더니 vs -다가
-더니: Observed sequence with time gap
- 비가 오더니 그쳤어요 (It was raining, and then stopped - observed)
-다가: Interrupted action
- 비가 오다가 그쳤어요 (It was raining, then stopped - factual sequence)
-더니 vs -(으)니까
-더니: Past observation → result
- 열심히 하더니 성공했어요 (Was working hard, and then succeeded)
-(으)니까: Direct causation (present/future)
- 열심히 하니까 성공할 거예요 (Since you work hard, you'll succeed)
-더니 vs -는데
-더니: Observed sequence leading to result
- 공부하더니 잤어요 (Was studying, and then slept)
-는데: Background context or contrast
- 공부하는데 시끄러워요 (I'm studying, but it's noisy)
Question Forms
Asking About Observations
Rare in questions, but possible:
- 뭐 하더니 그랬어요? (What were they doing, and then did that?)
- 어디 가더니 왔어요? (Where did they go, and then came back?)
Summary Table
| Type | Form | Example | Meaning |
|---|---|---|---|
| Basic observation | -더니 | 가더니 | was going, and then... |
| Weather | -더니 | 춥더니 | it was cold, and then... |
| Behavioral | -더니 | 울더니 | was crying, and then... |
| First person | -았/었더니 | 갔더니 | when I went, then... |
| Discovery | -았/었더니 | 봤더니 | when I looked, then... |
| Negative | 안 -더니 | 안 먹더니 | wasn't eating, then... |
Restrictions and Key Points
✅ Use -더니 when:
- Talking about someone else's observed actions
- Describing weather or situation changes you witnessed
- There's a time gap between the two events
- Emphasizing your observation of the sequence
❌ Don't use -더니 when:
- Talking about your own actions (use -았/었더니)
- The subject of both clauses is the speaker
- Making general statements without observation
✅ Use -았/었더니 when:
- Describing your own actions and their results
- Expressing discovery through your action
- Sharing your personal experience
Key Takeaways
- ✅ Observed sequence: Speaker witnessed first action/state
- ✅ Not for first person: Use -았/었더니 for speaker's actions
- ✅ Time gap: Indicates passage of time between events
- ✅ Cause-effect: Often shows observed causation
- ✅ Retrospective: Looking back at what happened
- ✅ Natural speech: Common for storytelling and reporting
-더니 is essential for reporting observations and sequences in Korean, allowing you to describe what you witnessed and how situations developed based on your direct observation.