Korean 'Because' & 'So': The Glue of Sentences (-아/어/여서)
아/어/여서 to explain natural reasons or sequential actions without using past tense in the first clause.
Grammar Rule in 30 Seconds
Use -아/어/여서 to connect two sentences where the first is the reason or the first step for the second.
- If the verb stem ends in ㅏ or ㅗ, add -아서 (e.g., 가다 → 가서).
- If the verb stem ends in anything else, add -어서 (e.g., 먹다 → 먹어서).
- For 하다 verbs, use -여서 (e.g., 공부하다 → 공부해서).
Overview
In Korean, connecting ideas fluidly is essential for natural communication. The connective ending -아/어/여서 (romanized as -a/eo/yeoseo) serves as a versatile linguistic "glue," primarily indicating cause/reason or sequential actions. It's a foundational grammatical structure at the A2 CEFR level, enabling learners to express why something happened or how a series of events unfolds.
Unlike some Western languages that might rely on separate sentences or conjunctions, Korean often integrates these relationships directly within a single clause structure, making the flow of conversation more cohesive and concise. Mastering -아/어/여서 moves you beyond simple, disjointed sentences towards a more sophisticated and native-like expression, crucial for both understanding and being understood in everyday situations.
This grammar pattern is frequently encountered in various contexts, from casual conversations to formal settings, and its nuanced understanding is key to grasping the logical progression of thoughts in Korean. It is particularly common when expressing apologies, gratitude, or simply explaining personal states or observable phenomena. The structure inherently binds two clauses, where the first clause provides the background or prerequisite for the second, fostering a sense of logical causality or necessary progression.
How This Grammar Works
-아/어/여서 primarily functions in two distinct, yet related, ways:-아/어/여서 indicates that the preceding clause (Clause 1) is the objective and generally accepted reason for the following clause (Clause 2). This means the reason presented is typically a factual statement, a physical state, an emotional condition, or an observable circumstance that leads to a subsequent outcome. It's often used when the reason is universally understood or an unavoidable consequence.비가 와서 길이 막혔어요.(비가 와서 길이 막혔어요. / bi-ga wa-seo gil-i mak-hyeot-eo-yo.) Because it rained, the road was blocked. Here, the rain is an objective reason for the road being blocked.피곤해서 일찍 잤어요.(피곤해서 일찍 잤어요. / pi-gon-hae-seo il-jjik jat-sseo-yo.) Because I was tired, I slept early. Tiredness is a direct, objective reason for sleeping early.몸이 안 좋아서 병원에 갔어요.(몸이 안 좋아서 병원에 갔어요. / mom-i an joh-a-seo byeong-won-e gat-sseo-yo.) Because I wasn't feeling well, I went to the hospital. Sickness is a clear reason for visiting a doctor.
죄송합니다 / joe-song-ham-ni-da) or gratitude (고맙습니다 / go-map-sseum-ni-da), as the reason for the apology/thanks is typically an objective action or situation.-아/어/여서 connects two or more actions, indicating that the first action logically or necessarily precedes the second. The second action cannot occur without the first one having taken place. This is not merely a chronological listing of events (like -고), but rather a sequence where the initial action sets up or enables the subsequent action.은행에 가서 돈을 찾았어요.(은행에 가서 돈을 찾았어요. / eun-haeng-e ga-seo don-eul chat-at-sseo-yo.) I went to the bank and withdrew money. You must go to the bank before you can withdraw money there.책을 읽어서 내용을 이해했어요.(책을 읽어서 내용을 이해했어요. / chaek-eul ilg-eo-seo nae-yong-eul i-hae-haet-sseo-yo.) I read the book and understood the content. Understanding follows the act of reading.창문을 열어서 시원해졌어요.(창문을 열어서 시원해졌어요. / chang-mun-eul yeol-eo-seo si-won-hae-jyeot-sseo-yo.) I opened the window, and it became cool. Opening the window is a necessary step for the room to cool down.
-아/어/여서 that differentiate it from other connective endings:- No Past Tense in the First Clause: The most significant rule is that the verb or adjective preceding
-아/어/여서cannot be in the past tense. Even if the entire event occurred in the past, the tense marker (-았/었/였-) is only applied to the final verb of the sentence. This is because Korean views the two clauses connected by-아/어/여서as a single, unified action or state with a single overall tense. The initial action or state is merely the background or precondition for the main event. It implies that the event described in the first clause is either ongoing or immediately relevant to the state/action in the second clause, whose tense then anchors the entire statement. - Incorrect:
밥을 먹었어서 배불러요.(X) (I ate, therefore I am full.) - Correct:
밥을 먹어서 배불러요.(밥을 먹어서 배불러요. / bap-eul meog-eo-seo bae-bul-leo-yo.) Because I ate, I am full. (The past action of eating is the reason for the current state of fullness.)
- Incompatible with Imperatives, Suggestions, and Volitional Expressions: You cannot use
-아/어/여서when the second clause expresses a command (-으세요/ -eu-se-yo), a suggestion (-ㅂ시다/ -b-si-da,-을까요?/ -eul-kka-yo?), or strong volition/conjecture (-겠-/ -get-). This is because-아/어/여서introduces an objective reason or a factual sequence. Commands and suggestions, however, are subjective and volitional. It would be illogical to present an objective fact as the direct reason for a command or suggestion, as commands/suggestions stem from the speaker's will or desire, not a universally accepted consequence of the preceding clause. For such contexts,-(으)니까is the appropriate choice, as it can convey a personal justification or a recently discovered reason for a directive. - Incorrect:
날씨가 좋아서 산책 가세요.(X) (Because the weather is good, go for a walk.) - Correct:
날씨가 좋으니까 산책 가세요.(날씨가 좋으니까 산책 가세요. / nal-ssi-ga joh-eu-ni-kka san-chaek ga-se-yo.) Since the weather is good, go for a walk. (The speaker's judgment about the weather is the basis for the suggestion.) - Incorrect:
피곤해서 쉬겠어요.(X) (Because I'm tired, I will rest.) - More Natural:
피곤해서 쉬려고 해요.(피곤해서 쉬려고 해요. / pi-gon-hae-seo swi-ryeo-go hae-yo.) Because I'm tired, I intend to rest. (Or)피곤하니까 쉬겠어요.(피곤하니까 쉬겠어요. / pi-gon-ha-ni-kka swi-get-sseo-yo.) Since I'm tired, I will rest. The incompatibility with-겠어요in the second clause generally holds when expressing the speaker's direct intention or strong conjecture as a direct consequence of the objective reason given by-아/어/여서. However, it can be used with forms like~어야겠어요(must/should) or for expressing an inevitable inability (e.g.,바빠서 못 가겠어요./ ba-ppa-seo mot ga-get-sseo-yo. - Because I'm busy, I won't be able to go.), where the objective reason prevents an action.
Formation Pattern
-아/어/여서 largely follows the vowel harmony rules similar to the polite present tense ending -아/어/여요 (just remove the 요). This ensures a natural flow and phonetic cohesion in speech.
ㅏ or ㅗ: Add -아서 (-a-seo). The first clause takes the ㅏ form.
가다 (to go) → 가 + 아서 → 가서 (가서 / ga-seo)
오다 (to come) → 오 + 아서 → 와서 (와서 / wa-seo) (Contraction of 오아서)
보다 (to see) → 보 + 아서 → 봐서 (봐서 / bwa-seo) (Contraction of 보아서)
알다 (to know) → 알 + 아서 → 알아서 (알아서 / a-ra-seo)
ㅏ or ㅗ (e.g., ㅓ, ㅜ, ㅣ, ㅡ, ㅔ, ㅐ): Add -어서 (-eo-seo). The first clause takes the ㅓ form.
먹다 (to eat) → 먹 + 어서 → 먹어서 (먹어서 / meog-eo-seo)
읽다 (to read) → 읽 + 어서 → 읽어서 (읽어서 / ilg-eo-seo)
마시다 (to drink) → 마시 + 어서 → 마셔서 (마셔서 / ma-syeo-seo) (Contraction of 마시어서)
배우다 (to learn) → 배우 + 어서 → 배워서 (배워서 / bae-wo-seo) (Contraction of 배우어서)
없다 (to not have/exist) → 없 + 어서 → 없어서 (없어서 / eop-sseo-seo)
하다: It always changes to -하여서, which commonly contracts to -해서 (-hae-seo). This is a remnant of an older phonetic change and is now a fixed pattern.
공부하다 (to study) → 공부하여서 → 공부해서 (공부해서 / gong-bu-hae-seo)
운동하다 (to exercise) → 운동하여서 → 운동해서 (운동해서 / un-dong-hae-seo)
미안하다 (to be sorry) → 미안하여서 → 미안해서 (미-an-hae-seo)
-아/어/여서 is attached. These irregularities are common across many Korean grammatical endings that begin with a vowel.
ㄷ Irregular Verbs: Verbs with a stem ending in ㄷ (e.g., 듣다, 걷다, 묻다) change ㄷ to ㄹ when followed by a vowel. Since -어서 begins with a vowel, this applies.
듣다 (to listen) → 들 + 어서 → 들어서 (들어서 / deul-eo-seo)
걷다 (to walk) → 걸 + 어서 → 걸어서 (걸어서 / geol-eo-seo)
묻다 (to ask) → 물 + 어서 → 물어서 (물어서 / mul-eo-seo)
받다 (to receive), 닫다 (to close), 믿다 (to believe) are regular: 받아서, 닫아서, 믿어서 because ㄷ is part of their inherent meaning and not subject to the sound change.)
ㅂ Irregular Verbs/Adjectives: Stems ending in ㅂ (e.g., 춥다, 덥다, 아름답다) change ㅂ to ㅜ (or ㅗ if the preceding vowel is ㅗ, though ㅗ is rare) when followed by a vowel. Then, combine with -어서 or -아서 according to vowel harmony.
춥다 (to be cold) → 추우 + 어서 → 추워서 (추워서 / chu-wo-seo)
덥다 (to be hot) → 더우 + 어서 → 더워서 (더워서 / deo-wo-seo)
아름답다 (to be beautiful) → 아름다우 + 아서 → 아름다워서 (아름다워서 / a-reum-da-wo-seo)
입다 (to wear), 잡다 (to catch), 좁다 (to be narrow) are regular: 입어서, 잡아서, 좁아서.)
르 Irregular Verbs/Adjectives: Stems ending in 르 (e.g., 모르다, 빠르다, 부르다) when followed by 아/어 drop ㅡ, and the ㄹ sound is doubled by adding ㄹ to the preceding syllable and retaining the ㄹ for the next syllable. The choice between -라 and -러 depends on the vowel preceding 르.
르 is ㅏ or ㅗ: 르 becomes 라 + 서
모르다 (to not know) → 모르 → 몰라 + 서 → 몰라서 (몰라서 / mol-la-seo)
고르다 (to choose) → 고르 → 골라 + 서 → 골라서 (골라서 / gol-la-seo)
르 is not ㅏ or ㅗ: 르 becomes 러 + 서
부르다 (to sing / to call) → 부르 → 불러 + 서 → 불러서 (불러서 / bul-leo-seo)
빠르다 (to be fast) → 빠르 → 빨라 + 서 → 빨라서 (빨라서 / ppal-la-seo)
ㅎ Irregular Adjectives: Adjectives with stems ending in ㅎ (often colors like 빨갛다 (to be red), 까맣다 (to be black), or states like 어떻다 (how)) drop ㅎ and add ㅐ before 서.
빨갛다 (to be red) → 빨개 + 서 → 빨개서 (빨개서 / ppal-gae-seo)
노랗다 (to be yellow) → 노래 + 서 → 노래서 (노래서 / no-rae-seo)
어떻다 (how) → 어때 + 서 → 어때서 (어때서 / eo-ttae-seo)
ㅅ Irregular Verbs: Verbs with a stem ending in ㅅ (e.g., 낫다, 짓다, 잇다) drop the ㅅ when followed by a vowel. Since -아/어 starts with a vowel, this applies.
낫다 (to be better/recover) → 나 + 아서 → 나아서 (나아서 / na-a-seo)
짓다 (to build/make) → 지 + 어서 → 지어서 (지어서 / ji-eot-seo)
잇다 (to connect) → 이 + 어서 → 이어서 (이어서 / i-eot-seo)
웃다 (to laugh), 벗다 (to take off) are regular: 웃어서, 벗어서.)
-아/어/여서 connective for various verb and adjective types.
-아/어/여서 Form | Romanization | Translation |
ㅏ, ㅗ | Add -아서 | 가다 (to go) | 가서 | ga-seo | Going and / Because I go |
오다 (to come) | 와서 | wa-seo | Coming and / Because I come |
-어서 | 먹다 (to eat) | 먹어서 | meog-eo-seo | Eating and / Because I eat |
배우다 (to learn) | 배워서 | bae-wo-seo | Learning and / Because I learn |
하다 verbs/adjs | Change to -해서 | 공부하다 (to study) | 공부해서 | gong-bu-hae-seo | Studying and / Because I study |
ㄷ irregular | ㄷ → ㄹ + -어서 | 듣다 (to listen) | 들어서 | deul-eo-seo | Listening and / Because I listen |
ㅂ irregular | ㅂ → ㅜ/ㅗ + -아서/어서 | 춥다 (to be cold) | 추워서 | chu-wo-seo | Being cold and / Because it's cold |
르 irregular | Drop ㅡ, add ㄹ + -라/러 + 서 | 모르다 (not know) | 몰라서 | mol-la-seo | Not knowing and / Because I don't know |
ㅎ irregular | Drop ㅎ, add ㅐ + 서 | 빨갛다 (to be red) | 빨개서 | ppal-gae-seo | Being red and / Because it's red |
ㅅ irregular | Drop ㅅ + -아서/어서 | 낫다 (to recover) | 나아서 | na-a-seo | Recovering and / Because I recover |
When To Use It
-아/어/여서 is key to using it effectively and avoiding common pitfalls. Its primary applications fall into the two categories discussed: expressing reasons/causes and sequential actions, each with specific nuances.-아/어/여서 when the first clause provides a clear, objective, and generally accepted reason for the state or action in the second clause. This is particularly common in the following situations, where the reason is often a statement of fact or an observable condition.- Apologies and Gratitude: This is a very common and natural use in Korean. The reason for being sorry or thankful is typically an action or situation that is clearly identifiable.
늦어서 죄송합니다.(늦어서 죄송합니다. / neut-eot-seo joe-song-ham-ni-da.) I am sorry for being late. (The act of being late is the objective reason for the apology.)도와줘서 고마워요.(도와줘서 고마워요. / do-wa-jwo-seo go-ma-wo-yo.) Thank you for helping me. (The act of helping is the objective reason for gratitude.)기다리게 해서 미안해요.(기다리게 해서 미안해요. / gi-da-ri-ge hae-seo mi-an-hae-yo.) I'm sorry for making you wait. (The action of causing waiting is the objective reason for the apology.)
- Explaining Physical or Emotional States: When your reason is a bodily sensation, a feeling, or a psychological state that objectively leads to a certain action or condition.
배고파서 밥을 먹었어요.(배고파서 밥을 먹었어요. / bae-go-pa-seo bap-eul meog-eo-sseo-yo.) Because I was hungry, I ate. (Hunger is a direct, objective motivator for eating.)졸려서 커피를 마셨어요.(졸려서 커피를 마셨어요. / jol-lyeo-seo keo-pi-reul ma-syeot-sseo-yo.) Because I was sleepy, I drank coffee. (Sleepiness objectively leads to drinking coffee for wakefulness.)슬퍼서 울었어요.(슬퍼서 울었어요. / seul-peo-seo ul-eo-sseo-yo.) Because I was sad, I cried. (Sadness is a direct cause for crying.)
- Describing Observable Facts or Conditions: When the reason is an external circumstance, a factual condition, or an event that clearly dictates the outcome.
날씨가 좋아서 산책했어요.(날씨가 좋아서 산책했어요. / nal-ssi-ga joh-a-seo san-chaek-haet-sseo-yo.) Because the weather was good, I took a walk. (Good weather is an objective condition enabling a walk.)길이 막혀서 회의에 늦었어요.(길이 막혀서 회의에 늦었어요. / gil-i mak-hyeo-seo hoe-ui-e neut-eot-sseo-yo.) Because the road was blocked, I was late for the meeting. (Traffic is an objective impediment.)방이 더워서 에어컨을 켰어요.(방이 더워서 에어컨을 켰어요. / bang-i deo-wo-seo e-eo-keon-eul kyeot-sseo-yo.) Because the room was hot, I turned on the air conditioner. (A hot room is an objective reason to use AC.)
-아/어/여서 when the first action is a necessary, logical, or preparatory step for the second action. The connection implies that the second action could not occur, or would not make sense, without the first having taken place. This is not simply chronological, but causally or logically linked.- Actions with Inherent Precedence: Often used with verbs of movement followed by another action at the destination, where arrival is a prerequisite.
집에 가서 쉬세요.(집에 가서 쉬세요. / jib-e ga-seo swi-se-yo.) Go home and rest. (You must arrive home before you can rest there.)도서관에 가서 책을 빌렸어요.(도서관에 가서 책을 빌렸어요. / do-seo-gwan-e ga-seo chaek-eul bil-lyeot-sseo-yo.) I went to the library and borrowed a book. (Borrowing is only possible after arriving at the library.)수업을 듣고서 숙제를 했어요.(수업을 듣고서 숙제를 했어요. / su-eop-eul deut-go-seo suk-je-reul haet-sseo-yo.) I attended class and then did my homework. (The class provides the context/content for the homework.)
- Actions Forming a Single Process or Procedure: When multiple actions combine to form a complete event or task, where the first action directly enables the second.
편지를 써서 부쳤어요.(편지를 써서 부쳤어요. / pyeon-ji-reul sse-seo bu-chyeot-sseo-yo.) I wrote the letter and sent it. (Sending is contingent on the letter being written first.)사진을 찍어서 친구에게 보냈어요.(사진을 찍어서 친구에게 보냈어요. / sa-jin-eul jjik-eo-seo chin-gu-e-ge bo-naet-sseo-yo.) I took a picture and sent it to a friend. (The picture must exist before it can be sent.)문을 열어서 들어오세요.(문을 열어서 들어오세요. / mun-eul yeol-eo-seo deul-eo-o-se-yo.) Open the door and come in. (Opening the door is the necessary preceding action for entering.)
-아/어/여서 can indicate a temporal sequence, its core meaning always includes the idea that the first clause either causes the second or is a necessary prerequisite for it. If the actions are merely chronological without a strong cause/effect or logical dependency, -고 (and then) is generally more appropriate. The choice between -아/어/여서 and -고 depends on whether the speaker wishes to emphasize a logical connection or simply a list of events.Common Mistakes
-아/어/여서 due to its nuanced application and strict rules. Awareness of these common errors will significantly improve your accuracy and help you sound more natural.- 1The Past Tense Trap: This is arguably the most frequent and persistent mistake. As stated, the clause preceding
-아/어/여서never takes past tense marking (-았/었/였-). Learners often mistakenly try to convey a past reason by conjugating the first verb/adjective into the past tense, mirroring English constructions.
- Incorrect:
어제 영화를 봤어서 재미있었어요.(X) (Because I watched the movie yesterday, it was fun.) - Correct:
어제 영화를 봐서 재미있었어요.(어제 영화를 봐서 재미있었어요. / eo-je yeong-hwa-reul bwa-seo jae-mi-it-sseo-yo.) Because I watched the movie yesterday, it was fun. - Explanation: In Korean, the entire statement
영화(를) 봐서 재미있었어요is treated as a single event or coherent chain of cause-and-effect with the past tense applied only to the final verb (재미있었어요). The-아/어/여서simply connects the preceding event or state (영화(를) 보다) as the reason or preceding action, whose timing is understood in relation to the main clause. The temporal information is contained within the final clause or implied by context. The structure[Action 1 (non-past)] + -아/어/여서 + [Action 2 (Tense)]implies that the entire chain of events occurred at the tense indicated by Action 2.
- 1Using with Imperatives, Suggestions, or Volition: This is a critical functional restriction.
-아/어/여서is fundamentally incompatible with second clauses that are commands, suggestions, or express strong personal intention/conjecture. This is a core semantic distinction to grasp.
- Incorrect:
비가 와서 우산을 가져가세요.(X) (Because it's raining, take an umbrella.) - Correct:
비가 오니까 우산을 가져가세요.(비가 오니까 우산을 가져가세요. / bi-ga o-ni-kka u-san-eul ga-jyeo-ga-se-yo.) Since it's raining, take an umbrella. - Explanation:
-아/어/여서primarily provides an objective reason. A command or suggestion (-으세요,-ㅂ시다,-을까요?) is a subjective expression of will, advice, or an appeal. Linking an objective fact to a subjective directive with-아/어/여서creates a logical disconnect.-(으)니까, on the other hand, is specifically designed to give a subjective reason or justification for a command or suggestion, often implying the speaker's personal judgment or a newly discovered fact that prompts the directive. - Incorrect:
내일 바빠서 쉬겠어요.(X) (Because I'm busy tomorrow, I will rest.) - This sounds slightly awkward as쉬겠어요expresses the speaker's strong will or intention. - More Natural:
내일 바빠서 쉬려고 해요.(내일 바빠서 쉬려고 해요. / nae-il ba-ppa-seo swi-ryeo-go hae-yo.) Because I'm busy tomorrow, I intend to rest. (Or, using-(으)니까for a subjective decision):내일 바쁘니까 쉬겠어요.(내일 바쁘니까 쉬겠어요. / nae-il ba-ppeu-ni-kka swi-get-sseo-yo.) Since I'm busy tomorrow, I will rest. While-겠어요in general intention contexts doesn't pair well, it can be used with-아/어/여서when expressing an inevitable outcome or inability due to the objective reason (e.g.,교통 체증이 심해서 늦겠어요./ gyo-tong che-jeung-i sim-hae-seo neut-get-sseo-yo. - Because the traffic is bad, I will be late. Here,~겠어요expresses likelihood/inevitability, not intention).
- 1Confusion with
-고(Simple Chronological Sequence): While both-아/어/여서(sequential actions) and-고(and then) connect verbs chronologically, their implications differ significantly. Failing to distinguish them can lead to unnatural-sounding sentences.
-아/어/여서 (Sequential/Causal) | -고 (And then / Listing) |은행에 가서 돈을 찾았어요. (은행에 가서 돈을 찾았어요. / eun-haeng-e ga-seo don-eul chat-at-sseo-yo.) Went to the bank to withdraw money. (Going is a necessary step.) | 빵을 먹고 커피를 마셨어요. (빵을 먹고 커피를 마셨어요. / ppang-eul meog-go keo-pi-reul ma-syeot-sseo-yo.) Ate bread, and then drank coffee. (Two separate actions in time.) |문을 열어서 들어갔어요. (문을 열어서 들어갔어요. / mun-eul yeol-eo-seo deul-eo-gat-sseo-yo.) Opened the door to enter. (Opening precedes and enables entry.) | 옷을 입고 학교에 갔어요. (옷을 입고 학교에 갔어요. / ot-eul ip-go hak-gyo-e gat-sseo-yo.) Put on clothes, and then went to school. (These are chronological but not causally linked in the same way; one could dress at school.) |피곤해서 잤어요. / pi-gon-hae-seo jat-sseo-yo. - Because I was tired, I slept.) | Rarely implies cause/effect. Primarily a chronological connector. |- Example Contrast:
친구를 만나서 영화를 봤어요.(친구를 만나서 영화를 봤어요. / chin-gu-reul man-na-seo yeong-hwa-reul bwat-sseo-yo.) I met a friend and then watched a movie with them. (Meeting is a prerequisite for watching with that specific friend.)친구를 만나고 영화를 봤어요.(친구를 만나고 영화를 봤어요. / chin-gu-reul man-na-go yeong-hwa-reul bwat-sseo-yo.) I met a friend, and then I watched a movie. (Two separate chronological events; the movie might have been watched alone after meeting the friend, or with a different group.)
- 1Overuse in Unrelated Events: Do not use
-아/어/여서if the first event does not directly cause or logically lead to the second. If you're simply listing things you did without emphasizing a causal or sequential dependency,-고is almost always more natural.
- Incorrect:
아침에 일어나서 빵을 먹어서 영화를 봤어요.(X) (I woke up, ate bread, and watched a movie.) - Correct:
아침에 일어나고 빵을 먹고 영화를 봤어요.(아침에 일어나고 빵을 먹고 영화를 봤어요. / a-chim-e il-eo-na-go ppang-eul meok-go yeong-hwa-reul bwat-sseo-yo.) I woke up, ate bread, and watched a movie. (Using-고is correct here for a simple list of actions.)
- 1Confusion with
-(으)니까(Subjective Reason/Discovery): While both express reasons, the choice between-아/어/여서and-(으)니까depends on the nature of the reason and the type of the second clause.
-아/어/여서 (Objective Reason) | -(으)니까 (Subjective Reason / Discovery) |피곤해서 일찍 잤어요. (피곤해서 일찍 잤어요. / pi-gon-hae-seo il-jjik jat-sseo-yo.) Because I was tired, I slept early. (Tiredness is an objective state leading to sleep.) | 피곤하니까 일찍 자세요. (피곤하니까 일찍 자세요. / pi-gon-ha-ni-kka il-jjik ja-se-yo.) Since you're tired, sleep early. (Speaker's advice based on observing tiredness.) |날씨가 좋아서 기분이 좋아요. (날씨가 좋아서 기분이 좋아요. / nal-ssi-ga joh-a-seo gi-bun-i joh-a-yo.) Because the weather is good, I feel good. (Good weather objectively affects mood.) | 날씨가 좋으니까 나들이 갑시다. (날씨가 좋으니까 나-deul-i gap-si-da.) Since the weather is good, let's go out. (Speaker's suggestion based on good weather.) |- A helpful way to remember: Think of
-아/어/여서as stating a universally acknowledged fact that leads to a result. Think of-(으)니까as stating a personal judgment or a newly realized fact that leads to a decision or action, often a command or suggestion.
Real Conversations
-아/어/여서 is a highly practical and frequently used connective in everyday Korean. Observing its usage in various contexts reveals its versatility and natural flow in expressing logical connections.
1. Apologies and Gratitude (Polite, 해요체/합니다체):
This is one of the most fundamental applications, often encountered in both casual and formal interactions.
- Scenario: You're late to an important meeting with a senior colleague.
- 죄송합니다. 차가 많이 막혀서 늦었습니다. (죄송합니다. 차가 많이 막혀서 늦었습니다. / joe-song-ham-ni-da. cha-ga man-i mak-hyeo-seo neut-eot-sseum-ni-da.) I apologize. Because the car was very backed up, I am late.
- Scenario: A friend helps you move heavy boxes.
- 도와줘서 정말 고마워요! (도와줘서 정말 고마워요! / do-wa-jwo-seo jeong-mal go-ma-wo-yo!) Thank you so much for helping!
- Scenario: Apologizing for sending an email with incorrect information to a client.
- 정보를 잘못 드려서 죄송합니다. (정보를 잘못 드려서 죄송합니다. / jeong-bo-reul jal-mot deu-ryeo-seo joe-song-ham-ni-da.) I apologize for giving you the wrong information.
2. Explaining Reasons/Circumstances (Casual to Polite):
-아/어/여서 is your go-to for explaining why things are the way they are, or why you did something.
- Scenario: Explaining why you can't meet a friend for dinner.
- A: 오늘 저녁에 시간 돼요? 같이 밥 먹을까요? (오늘 저녁에 시간 돼요? 같이 밥 먹을까요? / o-neul jeo-nyeok-e si-gan dwae-yo? ga-chi bap meog-eul-kka-yo?) Do you have time this evening? Shall we eat together?
- B: 미안, 내일 시험이 있어서 오늘은 공부해야 해. (미안, 내일 시험이 있어서 오늘은 공부해야 해. / mi-an, nae-il si-heom-i it-sseo-seo o-neul-eun gong-bu-hae-ya hae.) Sorry, because I have an exam tomorrow, I have to study today. (해체 / hae-che - casual)
- Scenario: Explaining why you are staying indoors on a nice day.
- 날씨가 너무 더워서 밖에 나가기 싫어요. (날씨가 너무 더워서 밖에 나가기 싫어요. / nal-ssi-ga neo-mu deo-wo-seo bak-ke na-ga-gi silh-eo-yo.) Because the weather is too hot, I don't want to go outside. (해요체 / hae-yo-che - polite informal)
- Scenario: Describing a traffic situation to a family member.
- 비가 많이 와서 길이 미끄러워요. 운전 조심해야겠어요. (비가 많이 와서 길이 미끄러워요. 운전 조심해야겠어요. / bi-ga man-i wa-seo gil-i mi-kkeu-reo-wo-yo. un-jeon jo-sim-hae-ya-get-sseo-yo.) Because it rained a lot, the road is slippery. I need to drive carefully. (해요체)
3. Describing Sequential Actions (Everyday Tasks/Processes):
This structure naturally describes steps or procedures where one action leads to the next.
- Scenario: Giving directions to a new place.
- 저 사거리에서 오른쪽으로 돌아서 쭉 가면 돼요. (저 사거리에서 오른쪽으로 돌아서 쭉 가면 돼요. / jeo sa-geo-ri-e-seo o-reun-jjok-eu-ro dol-a-seo jjuk ga-myeon dwae-yo.) Turn right at that intersection, and then go straight, and you'll be there. (해요체)
- Scenario: Recounting a day's activities.
- 학교에 가서 친구들을 만나서 같이 밥을 먹었어요. (학교에 가서 친구들을 만나서 같이 밥을 먹었어요. / hak-gyo-e ga-seo chin-gu-deul-eul man-na-seo ga-chi bap-eul meog-eo-sseo-yo.) I went to school, met my friends, and ate together. (해요체)
- Scenario: Describing what you did immediately after work.
- 퇴근하고 집에 와서 바로 저녁을 준비했어요. (퇴근하고 집에 와서 바로 저녁을 준비했어요. / toe-geun-ha-go jib-e wa-seo ba-ro jeo-nyeok-eul jun-bi-haet-sseo-yo.) After getting off work, I came home and immediately prepared dinner. (해요체)
4. Texting/Messaging (Informal, 해체):
In informal written communication, the structure remains consistent but might omit politeness endings.
- 피곤해서 오늘은 집에서 쉴게. (피곤해서 오늘은 집에서 쉴게. / pi-gon-hae-seo o-neul-eun jib-e-seo swil-ge.) I'm tired, so I'll rest at home today.
- 배고파서 뭐 시켜 먹을까 생각 중. (배고파서 뭐 시켜 먹을까 생각 중. / bae-go-pa-seo mwo si-kyeo meog-eul-kka saeng-gak jung.) I'm hungry, so I'm thinking about what to order and eat.
- 버스 놓쳐서 늦을 것 같아 ㅠㅠ (버스 놓쳐서 늦을 것 같아 ㅠㅠ / beo-sseu not-chyeo-seo neut-eul geot gat-a ㅠㅠ) I missed the bus, so I think I'll be late ㅠㅠ
These examples demonstrate how -아/어/여서 naturally connects clauses, creating a coherent narrative or explanation without sounding stiff or overly formal. It integrates smoothly into various politeness levels, making it indispensable for daily communication.
Quick FAQ
- Q: Can I use
-아/어/여서with nouns? - A: Not directly. For nouns, you typically use
(이)라서(for a reason/cause) or이어서(for a sequence). For example,학생이어서 공부해요.(학생이어서 공부해요. / hak-saeng-i-eo-seo gong-bu-hae-yo.) Because I am a student, I study. (Here,이어서is from이다(to be)).
- Q: Why is it often called both "because" and "so"?
- A: This reflects the direction of causality. When translated from Korean, the first clause is the
Conjugation Rules for -아/어/여서
| Verb Type | Ending | Example | Meaning |
|---|---|---|---|
|
ㅏ, ㅗ
|
-아서
|
가다 → 가서
|
Go and...
|
|
ㅓ, ㅜ, ㅣ, etc.
|
-어서
|
먹다 → 먹어서
|
Eat and...
|
|
하다
|
-해서
|
공부하다 → 공부해서
|
Study and...
|
|
ㄷ irregular
|
-어서
|
듣다 → 들어서
|
Listen and...
|
|
ㅂ irregular
|
-어서
|
춥다 → 추워서
|
Cold and...
|
|
ㄹ irregular
|
-어서
|
만들다 → 만들어서
|
Make and...
|
Common Contractions
| Full Form | Contraction |
|---|---|
|
가서
|
가서
|
|
보아서
|
봐서
|
|
되어서
|
돼서
|
Meanings
This ending connects two clauses where the first clause provides the reason, cause, or the first chronological step for the second clause.
Causal
Indicates a reason for the following action or state.
“비가 와서 집에 있어요.”
“피곤해서 일찍 잘 거예요.”
Sequential
Indicates the first step in a sequence of actions.
“학교에 가서 공부해요.”
“친구를 만나서 영화를 봤어요.”
Reference Table
| Form | Structure | Example |
|---|---|---|
|
Affirmative
|
Verb-아/어/여서
|
바빠서 못 가요.
|
|
Negative
|
안 + Verb-아/어/여서
|
안 먹어서 배고파요.
|
|
Adjective
|
Adj-아/어/여서
|
예뻐서 샀어요.
|
|
Past Tense (Final)
|
Verb-아/어/여서 + Verb-았/었
|
피곤해서 일찍 잤어요.
|
|
Sequence
|
Verb-아/어/여서 + Verb
|
씻고 나서 밥 먹어요.
|
|
Reason
|
Verb-아/어/여서 + Result
|
비가 와서 우산을 썼어요.
|
Formality Spectrum
바빠서 갈 수 없습니다. (Declining an invitation)
바빠서 못 가요. (Declining an invitation)
바빠서 못 가. (Declining an invitation)
바빠서 못 가! (Declining an invitation)
The Two Faces of -아/어/여서
Causality
- 이유 Reason
Sequence
- 순서 Order
Examples by Level
배가 고파서 먹어요.
I am hungry, so I eat.
더워서 물을 마셔요.
It is hot, so I drink water.
아파서 학교에 안 가요.
I am sick, so I don't go to school.
바빠서 못 만나요.
I am busy, so I can't meet.
숙제를 해서 선생님께 드렸어요.
I did my homework and gave it to the teacher.
돈이 없어서 영화를 못 봤어요.
I had no money, so I couldn't watch the movie.
길이 막혀서 늦었어요.
The road was blocked, so I was late.
친구를 만나서 밥을 먹었어요.
I met a friend and ate a meal.
날씨가 좋아서 공원에 산책하러 가요.
The weather is nice, so I'm going to the park for a walk.
열심히 공부해서 시험에 합격했어요.
I studied hard, so I passed the exam.
너무 놀라서 아무 말도 못 했어요.
I was so surprised that I couldn't say anything.
어제 야근을 해서 너무 피곤해요.
I worked overtime yesterday, so I'm very tired.
정부가 정책을 바꿔서 경제가 좋아졌어요.
The government changed the policy, so the economy improved.
기술이 발전해서 삶이 편리해졌어요.
Technology advanced, so life became convenient.
그는 실수를 해서 사과를 해야 해요.
He made a mistake, so he must apologize.
재료가 신선해서 음식이 맛있어요.
The ingredients are fresh, so the food is delicious.
예산이 부족해서 프로젝트를 중단해야 했습니다.
The budget was insufficient, so we had to stop the project.
그녀는 열정이 넘쳐서 모든 일을 완벽하게 처리해요.
She is full of passion, so she handles everything perfectly.
사건의 전말을 알게 되어서 마음이 편해졌어요.
I found out the truth of the case, so I feel at ease.
환경 오염이 심각해져서 대책이 필요해요.
Environmental pollution has become serious, so measures are needed.
본질을 꿰뚫어 보는 통찰력을 길러서 문제를 해결했어요.
I cultivated the insight to see through the essence, so I solved the problem.
역사적 맥락을 이해해서 문학 작품을 깊이 있게 감상할 수 있어요.
I understand the historical context, so I can appreciate literary works deeply.
그의 논리는 빈틈이 없어서 반박하기 어려웠습니다.
His logic was flawless, so it was difficult to refute.
시대의 변화를 수용해서 기업이 성장할 수 있었습니다.
The company was able to grow by embracing the changes of the era.
Easily Confused
Both mean 'because'.
Both connect sentences.
Both indicate cause.
Common Mistakes
먹었어서
먹어서
비가 와서 집에 가세요.
비가 오니까 집에 가세요.
가아서
가서
공부하서
공부해서
예뻤어서
예뻐서
가서 먹자
가니까 먹자
바쁘서
바빠서
숙제를 했어서 칭찬받았다.
숙제를 해서 칭찬받았다.
비가 와서 우산을 가져가세요.
비가 오니까 우산을 가져가세요.
그녀가 와서 보라고 했다.
그녀가 오니까 보라고 했다.
그는 아팠어서 못 왔다.
그는 아파서 못 왔다.
날씨가 좋아서 산책하자.
날씨가 좋으니까 산책하자.
돈이 없어서 빌려줘.
돈이 없으니까 빌려줘.
Sentence Patterns
___(으)니까/아서/어서 ___(으)세요.
___(이)라서/아서/어서 ___(으)ㄹ 거예요.
___(이)라서/아서/어서 ___(으)ㅆ어요.
___(이)라서/아서/어서 ___(으)ㄴ 것 같아요.
Real World Usage
배고파서 밥 먹으러 가!
맛있어서 또 주문했어요.
경험이 많아서 잘할 수 있습니다.
길을 몰라서 물어봤어요.
날씨 좋아서 공원 옴.
바빠서 회신이 늦었습니다.
Check the Vowel
No Tense in Clause 1
Use -니까 for Commands
Politeness Matters
Smart Tips
Use -아/어/여서 to connect the reason (traffic/bus) to the result (lateness).
Use -아/어/여서 to show the first step of your day.
Remember it always becomes -해서.
Adjectives follow the same vowel rules as verbs.
Pronunciation
Linking
The '서' is often pronounced clearly, but in fast speech, the '어' might blend.
Statement
바빠서 못 가요. ↘
Falling intonation for a standard statement.
Memorize It
Mnemonic
Think of '서' as 'So'. If you are 'So' (서) hungry, you eat.
Visual Association
Imagine a bridge connecting two islands. One island is the 'Reason', the other is the 'Result'. The bridge is labeled '-아/어/여서'.
Rhyme
Vowel ㅏ or ㅗ, add -아서, everything else, -어서, and 하다 becomes -해서!
Story
Min-su was tired (피곤해서). He went home (집에 가서). He slept (잤어요). The glue -아/어/여서 kept his day moving.
Word Web
Challenge
Write 3 sentences about your morning using -아/어/여서 to connect your actions.
Cultural Notes
Koreans value logical flow. Using this grammar makes your speech sound more organized and polite.
In a professional setting, using this to explain delays is standard practice.
Friends use this to quickly explain their actions.
Derived from the connective particle -아/어/여 + 서 (from the verb 서다, meaning 'to stand').
Conversation Starters
오늘 왜 늦었어요?
왜 한국어를 공부해요?
오늘 기분이 어때요?
왜 그 영화를 좋아해요?
Journal Prompts
Common Mistakes
Test Yourself
배가 (고프다) ___ 밥을 먹었어요.
Find and fix the mistake:
비가 왔어서 집에 갔어요.
Which is correct?
Arrange the words in the correct order:
All words placed
Click words above to build the sentence
I am busy, so I cannot go.
Answer starts with: 바빠서...
운동하다 + 아/어/여서
Match each item on the left with its pair on the right:
날씨가 좋다. 공원에 가요.
Score: /8
Practice Exercises
8 exercises배가 (고프다) ___ 밥을 먹었어요.
Find and fix the mistake:
비가 왔어서 집에 갔어요.
Which is correct?
먹었어요 / 배가 / 고파서 / 밥을
I am busy, so I cannot go.
운동하다 + 아/어/여서
비가 와서...
날씨가 좋다. 공원에 가요.
Score: /8
Practice Bank
10 exercises지금 너무 ____ 못 만나요.
Translate: I ate a lot, so my stomach hurts.
커피를 마셨어서 잠이 안 와요.
추워서 / 입었어요 / 코트를
Select the sentence where actions are logically linked:
Match the pairs:
답장이 ____ 죄송합니다. (늦다)
위험해서 가지 마세요.
Translate: I met a friend and we drank coffee.
Pick the correct sentence:
Score: /10
FAQ (8)
Only in the final clause. The first clause must be in the plain stem form.
It always becomes -해서.
It can be used in both. The formality is determined by the final verb.
The grammar is designed for objective reasons, not subjective requests.
-아/어/여서 is for general reasons; -니까 is for subjective reasons or commands.
Yes, it works for both verbs and adjectives.
Adding past tense markers to the first clause.
No, it also means 'and then' for sequential actions.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
〜て (te-form)
Korean has more strict constraints on tense and mood in the first clause.
porque
Korean combines cause and sequence into one particle.
weil
Korean -아/어/여서 does not change the word order of the second clause.
parce que
Korean is more versatile in connecting actions.
لأن (li-anna)
Korean is a suffix attached to the verb stem.
因为 (yīnwèi)
Korean is an agglutinative suffix.
Learning Path
Prerequisites
Related Videos
Related Grammar Rules
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Overview The Korean grammar pattern `-(으)러 가다/오다` (Romanization: `-(eu)reo gada/oda`) is a fundamental A2-level co...
Korean Result Grammar: So That & Until (-도록)
Overview This guide introduces the Korean connective ending `도록` (pronounced `dorok`), a versatile grammatical tool cr...
Observing Changes & Results (-더니)
Overview `-더니` is an upper-intermediate (CEFR B2) Korean connective ending that expresses a direct observation made by...
