-더니 expresses that the speaker observed something in the past, and then a subsequent action or change occurred. It means "I noticed/saw [A], and then [B]" or "[A] was happening, and then [B]."
Structure
Verb/Adjective stem + -더니
Breakdown:
- -더니: Retrospective observation + subsequent change
- Speaker's past observation
- Followed by resulting action/state
- Implies cause and effect or sequential change
Literal meaning: "I saw/observed [A], and then [B] happened"
Formation Rules
With All Verbs and Adjectives
Stem + -더니:
- 가다 → 가더니 (went, and then...)
- 먹다 → 먹더니 (was eating, and then...)
- 아프다 → 아프더니 (was sick, and then...)
- 좋다 → 좋더니 (was good, and then...)
- 피곤하다 → 피곤하더니 (was tired, and then...)
With 이다
Noun + 이더니/더니:
With final consonant: 이더니
- 학생이더니 (was a student, and then...)
- 겨울이더니 (was winter, and then...)
No final consonant: 더니
- 의사더니 (was a doctor, and then...)
Core Meaning: Observation + Change
Noticed Then Changed
First observation, then different state:
- 아프더니 나았어요 (They were sick, and then got better)
- 비가 오더니 그쳤어요 (It was raining, and then stopped)
- 춥더니 따뜻해졌어요 (It was cold, and then got warm)
- 울더니 웃었어요 (They were crying, and then laughed)
Sequential Events
One thing observed, another followed:
- 밥을 먹더니 잤어요 (They ate, and then slept)
- 공부하더니 나갔어요 (They were studying, and then went out)
- 책을 읽더니 TV를 봤어요 (They were reading, and then watched TV)
Cause and Effect
Observed cause leading to result:
- 피곤하더니 일찍 잤어요 (They were tired, so they slept early)
- 배고프더니 많이 먹었어요 (They were hungry, so they ate a lot)
- 추웠더니 감기 걸렸어요 (It was cold, and then they caught a cold)
Common Usage Patterns
Change in State
Transformation or shift:
- 화가 났더니 진정됐어요 (They were angry, then calmed down)
- 슬프더니 괜찮아졌어요 (They were sad, then became okay)
- 어렵더니 쉬워졌어요 (It was difficult, then became easy)
Weather/Time Changes
Natural progressions:
- 비가 오더니 날이 맑아졌어요 (It rained, then became clear)
- 아침이더니 벌써 저녁이에요 (It was morning, and now it's already evening)
- 봄이더니 여름이 왔어요 (It was spring, and summer came)
Actions and Results
One action leading to another:
- 열심히 공부하더니 합격했어요 (They studied hard, and then passed)
- 연습하더니 잘하게 됐어요 (They practiced, and became good at it)
- 많이 먹더니 배가 아파요 (They ate a lot, and now their stomach hurts)
Subject Restrictions
Usually 3rd Person or Non-Speaker
Typically not for speaker's own actions:
✅ 그가 아프더니 나았어요 (He was sick, then got better) ✅ 비가 오더니 그쳤어요 (It rained, then stopped)
❌ 내가 아프더니 나았어요 (Awkward - I was sick...)
Exception: Can be used for speaker's past self from current perspective
- 어렸을 때 작았더니 지금 컸어요 (I was small when young, now I'm tall)
Politeness Levels
Works with All Levels
Main clause determines politeness:
- 아프더니 나았습니다 (formal)
- 아프더니 나았어요 (polite)
- 아프더니 나았어 (casual)
Tense
Always Past Observation
-더니 inherently past:
- First clause is always past observation
- Second clause can be any tense
- 아프더니 지금 괜찮아요 (Was sick, now is okay)
Negative Forms
Wasn't, Then...
안 + Verb + -더니:
- 안 먹더니 지금 배고파해요 (They didn't eat, and now they're hungry)
- 안 자더니 피곤해 보여요 (They didn't sleep, and look tired)
Verb + -지 않더니:
- 먹지 않더니 배고파요 (They didn't eat, and are hungry)
- 오지 않더니 연락이 왔어요 (They didn't come, then contacted)
Common Expressions
Health Changes
- 아프더니 나았어요 (Was sick, then got better)
- 기침하더니 감기 걸렸어요 (Was coughing, then caught a cold)
- 피곤하더니 잤어요 (Was tired, then slept)
Weather Changes
- 비가 오더니 그쳤어요 (It rained, then stopped)
- 춥더니 따뜻해졌어요 (It was cold, then got warm)
- 흐리더니 맑아졌어요 (It was cloudy, then cleared up)
Emotional Changes
- 화가 났더니 진정됐어요 (Was angry, then calmed down)
- 울더니 웃었어요 (Was crying, then laughed)
- 슬프더니 행복해 보여요 (Was sad, now looks happy)
Time Progression
- 아침이더니 벌써 저녁이에요 (It was morning, already evening)
- 어제더니 오늘이네요 (It was yesterday, now it's today)
Actions and Consequences
- 먹더니 잤어요 (Ate, then slept)
- 공부하더니 시험 잘 봤어요 (Studied, then did well on test)
- 열심히 하더니 성공했어요 (Worked hard, then succeeded)
Comparison with Similar Patterns
-더니 vs -다가
-더니: Observation, then change (3rd person focus)
- 비가 오더니 그쳤어요 (It rained, then stopped - I observed)
- Speaker observed the whole sequence
-다가: While doing, then changed (speaker action)
- 비가 오다가 그쳤어요 (It was raining, then stopped - neutral)
- Can be any subject, focus on action switch
-더니 vs -았/었는데
-더니: Past observation + subsequent result
- 아프더니 나았어요 (Was sick, then got better)
- Two-part sequence with change
-았/었는데: Past background for current situation
- 아팠는데 지금 괜찮아요 (Was sick, but now okay)
- Contrast or background information
-더니 vs -고
-더니: Observation of sequence (3rd person)
- 먹더니 잤어요 (Ate, then slept - I observed)
- Retrospective observation
-고: Simple sequential connection
- 먹고 잤어요 (Ate and slept)
- Neutral sequence
Special Nuances
Often Implies Expectation
Result follows naturally from observation:
- 피곤하더니 잤어요 (Was tired, so naturally slept)
- The second part often expected from first
Can Show Surprise
Unexpected change:
- 싫다고 하더니 지금은 좋아해요 (Said they didn't like it, but now they do)
- Contradiction or surprising development
Time Gap
Can indicate passage of time:
- 어렸더니 이제 다 컸어요 (Was young, now all grown up)
- Shows transformation over time
Usage in Conversation
Reporting Others' Behavior
A: 민수는 어디 갔어? (Where did Minsu go?) B: 피곤하더니 집에 갔어요 (He was tired, so he went home)
Describing Changes
A: 날씨가 어때? (How's the weather?) B: 아까 비가 오더니 지금은 맑아요 (It was raining earlier, but now it's clear)
Commenting on Situations
A: 아기가 왜 울어? (Why is the baby crying?) B: 아까 놀더니 지금 졸려 보여요 (They were playing, now they look sleepy)
Summary Table
| Pattern | Example | Meaning | Subject |
|---|---|---|---|
| -더니 | 아프더니 나았어요 | Was sick, then got better | Usually 3rd |
| -다가 | 아프다가 나았어요 | Was sick, then got better | Any subject |
| -았/었는데 | 아팠는데 괜찮아요 | Was sick, but now okay | Any subject |
| -더라 | 아프더라 | I saw they were sick | 3rd person only |
Usage Context Guide
Use -더니 when:
- Describing observed changes in others
- Reporting sequential events you witnessed
- Explaining cause and effect from observation
- Commenting on weather/situation changes
- Showing transformation over time
Common contexts:
- Health changes (아프더니 나았다)
- Weather (비 오더니 그쳤다)
- Actions sequence (먹더니 잤다)
- Emotional states (울더니 웃었다)
- Time passage (어렸더니 컸다)
Register Note
Conversational
Natural in spoken Korean:
- Common in daily conversation
- Can be used in written narrative
- Not overly formal or casual
Key Takeaways
- ✅ Observation + change: Two-part sequence
- ✅ Usually 3rd person: About others or non-speaker
- ✅ Past observation: First part always past
- ✅ Sequential: One thing, then another
- ✅ Often causal: First part leads to second
- ✅ Can show surprise: Unexpected developments
- ✅ Very common: Essential conversational pattern
-더니 is essential for describing observed changes and sequential events in Korean, particularly when reporting what others did or how situations evolved based on your past observations.