-기 때문에 expresses formal causation and reasoning. It's more formal and explanatory than -(으)니까 or -아/어서, commonly used in writing, news, and formal situations.
Structure
Verb/Adjective stem + -기 때문에
Breakdown:
- -기: Nominalizing ending (makes verb into noun)
- 때문에: Because of, due to
- Combined: "Because of [doing/being]"
Literal meaning: "Because of the fact that..."
Formation Rules
All Verbs and Adjectives: -기 때문에
Uniform attachment regardless of final consonant:
- 가다 → 가기 때문에 (because [one] goes)
- 먹다 → 먹기 때문에 (because [one] eats)
- 읽다 → 읽기 때문에 (because [one] reads)
- 크다 → 크기 때문에 (because [it's] big)
- 작다 → 작기 때문에 (because [it's] small)
- 좋다 → 좋기 때문에 (because [it's] good)
ㄹ Irregular: Keep ㄹ + -기 때문에
No dropping of ㄹ:
- 살다 → 살기 때문에 (because [one] lives)
- 만들다 → 만들기 때문에 (because [one] makes)
- 팔다 → 팔기 때문에 (because [one] sells)
하다 Verbs: -하기 때문에
All 하다 verbs:
- 공부하다 → 공부하기 때문에 (because [one] studies)
- 일하다 → 일하기 때문에 (because [one] works)
- 바쁘다 → 바쁘기 때문에 (because [one is] busy)
Core Meaning: Formal Reasoning
Explanatory Statements
Formal explanations:
- 비가 오기 때문에 행사가 취소되었습니다 (Because it's raining, the event has been cancelled)
- 건강하기 때문에 운동을 열심히 합니다 (I exercise hard because I want to be healthy)
- 중요하기 때문에 잊지 마세요 (Don't forget because it's important)
Objective Reasons
Factual, logical causes:
- 경험이 많기 때문에 잘 할 수 있습니다 (I can do it well because I have a lot of experience)
- 시간이 없기 때문에 빨리 끝내야 합니다 (We must finish quickly because there's no time)
- 날씨가 좋기 때문에 사람이 많습니다 (There are many people because the weather is nice)
Written vs Spoken
More common in writing:
- News reports
- Academic papers
- Formal letters
- Official announcements
- Business communications
Less common in casual speech (use -(으)니까 or -아/어서 instead)
Common Usage Patterns
Formal Explanations
Professional contexts:
- 회의가 있기 때문에 먼저 갑니다 (I'm leaving first because I have a meeting)
- 중요한 시험이기 때문에 열심히 공부합니다 (I'm studying hard because it's an important exam)
- 법이기 때문에 지켜야 합니다 (You must follow it because it's the law)
Written Reports
News and articles:
- 교통사고가 발생하기 때문에 조심해야 합니다 (You must be careful because traffic accidents occur)
- 환경이 중요하기 때문에 보호해야 합니다 (We must protect it because the environment is important)
Official Statements
Announcements:
- 공사 중이기 때문에 우회하시기 바랍니다 (Please detour because construction is underway)
- 점검 중이기 때문에 잠시 기다려 주세요 (Please wait a moment because maintenance is in progress)
Tense with -기 때문에
Present Tense: -기 때문에
Current state/general truth:
- 비싸기 때문에 안 삽니다 (I won't buy it because it's expensive)
- 좋기 때문에 추천합니다 (I recommend it because it's good)
Past Tense: -았/었기 때문에
Past reason:
- 공부했기 때문에 합격했습니다 (I passed because I studied)
- 늦었기 때문에 택시를 탔습니다 (I took a taxi because I was late)
- 바빴기 때문에 못 갔습니다 (I couldn't go because I was busy)
Future Tense: -(으)ㄹ 것이기 때문에
Future reason (formal):
- 비쌀 것이기 때문에 준비하세요 (Prepare because it will be expensive)
- 어려울 것이기 때문에 미리 공부하세요 (Study in advance because it will be difficult)
Common Expressions
Formal Reasons
- 중요하기 때문에 (because it's important)
- 필요하기 때문에 (because it's necessary)
- 위험하기 때문에 (because it's dangerous)
- 바쁘기 때문에 (because [one is] busy)
Professional Contexts
- 회의가 있기 때문에 (because there's a meeting)
- 일이 많기 때문에 (because there's a lot of work)
- 규칙이기 때문에 (because it's a rule)
- 법이기 때문에 (because it's the law)
Academic Writing
- 연구 결과이기 때문에 (because it's a research result)
- 증명되었기 때문에 (because it's been proven)
- 사실이기 때문에 (because it's a fact)
Politeness Levels
Formal (합니다체)
- 비가 오기 때문에 우산을 가져가십시오 (Please take an umbrella because it's raining)
- 중요하기 때문에 꼭 기억하십시오 (Please remember because it's important)
Polite (해요체)
- 바쁘기 때문에 먼저 갈게요 (I'll go first because I'm busy)
- 어렵기 때문에 도와줄게요 (I'll help because it's difficult)
Casual (반말)
Less common in casual speech:
- 피곤하기 때문에 쉴게 (I'll rest because I'm tired)
- Usually replaced with: 피곤해서 쉴게 (more natural)
Negative Forms
Negative Reason
안 + Verb + -기 때문에:
- 안 좋기 때문에 바꿔야 합니다 (We must change it because it's not good)
- 안 비싸기 때문에 괜찮습니다 (It's okay because it's not expensive)
Verb + -지 않기 때문에:
- 좋지 않기 때문에 다시 합니다 (We'll do it again because it's not good)
- 비싸지 않기 때문에 살 수 있습니다 (We can buy it because it's not expensive)
Can't/Unable
못 + Verb + -기 때문에:
- 못 가기 때문에 죄송합니다 (I'm sorry because I can't go)
- 못 먹기 때문에 다른 것을 주세요 (Please give me something else because I can't eat it)
-기 때문에 vs Similar Patterns
-기 때문에 vs -(으)니까
-기 때문에: Formal, explanatory, written
- 비가 오기 때문에 행사가 취소되었습니다 (The event was cancelled because it's raining)
-(으)니까: Conversational, commands/suggestions
- 비가 오니까 우산 가져가세요 (It's raining, so take an umbrella)
-기 때문에 vs -아/어서
-기 때문에: Formal, can use with commands (formal style)
- 중요하기 때문에 기억하십시오 (Remember it because it's important)
-아/어서: Casual, CANNOT use with commands
- 중요해서 기억해요 (I remember it because it's important)
- 중요해서 기억하세요 ❌ (Incorrect)
-기 때문에 vs 때문에 (Noun + 때문에)
Verb + -기 때문에: Because [action/state]
- 바쁘기 때문에 (because [I am] busy)
Noun + 때문에: Because of [noun]
- 일 때문에 (because of work)
- 비 때문에 (because of rain)
Question Forms
Formal Questions
- 왜 늦었습니까? 교통 때문입니까? (Why are you late? Is it because of traffic?)
- Used more for answering than asking
Explanatory Responses
- 늦은 이유가 뭡니까? (What's the reason you're late?)
- 교통이 막히기 때문입니다 (It's because traffic was congested)
Summary Table
| Verb Type | Stem | -기 때문에 Form | Meaning |
|---|---|---|---|
| Vowel ending | 가다 | 가기 때문에 | because [one] goes |
| Consonant | 먹다 | 먹기 때문에 | because [one] eats |
| ㄹ irregular | 살다 | 살기 때문에 | because [one] lives |
| 하다 verb | 공부하다 | 공부하기 때문에 | because [one] studies |
| Adjective (vowel) | 크다 | 크기 때문에 | because [it's] big |
| Adjective (consonant) | 좋다 | 좋기 때문에 | because [it's] good |
Key Takeaways
- ✅ Formal causation: Professional and written contexts
- ✅ Explanatory tone: Objective, logical reasoning
- ✅ Uniform formation: Always -기 때문에 (no variations)
- ✅ Written preference: More common in formal writing
- ✅ Can use with commands: In formal style
- ✅ Less conversational: Use -(으)니까 or -아/어서 for casual speech
-기 때문에 is essential for formal communication, academic writing, and professional contexts where objective, explanatory reasoning is required in Korean.