-기 때문에 is a formal way to express reasons or causes. It means "because," "due to," or "owing to" and is commonly used in writing and formal speech.
Structure
Verb/Adjective stem + -기 때문에
Breakdown:
- -기: Nominalizing ending
- 때문에: Because of
Literal meaning: "Because of the fact that..."
Basic Pattern
All Verbs and Adjectives: -기 때문에
No conjugation variations:
- 가다 → 가기 때문에 (because go)
- 먹다 → 먹기 때문에 (because eat)
- 하다 → 하기 때문에 (because do)
- 좋다 → 좋기 때문에 (because good)
- 바쁘다 → 바쁘기 때문에 (because busy)
Simple rule: Add -기 때문에 to any stem
Formality Level
More Formal Than -아/어서 or -(으)니까
Formality ranking:
- -기 때문에 (Most formal)
- -(으)니까 (Formal)
- -아/어서 (Casual)
Used in:
- Written Korean
- Academic writing
- News reports
- Formal speeches
- Official explanations
- Business contexts
Less common in:
- Daily casual conversation
- Informal speech
- Chatting with friends
Core Usage: Formal Explanations
Giving Official Reasons
Formal contexts:
- 시간이 없기 때문에 못 갑니다 (Because there's no time, I can't go)
- 비가 오기 때문에 취소합니다 (Because it's raining, we're cancelling)
- 중요하기 때문에 확인해 주세요 (Because it's important, please check)
With Past Tense: -았/었기 때문에
Past Reason
Pattern: -았/었기 때문에
Examples:
- 갔기 때문에 (because went)
- 먹었기 때문에 (because ate)
- 했기 때문에 (because did)
- 좋았기 때문에 (because was good)
Usage: Explaining past reasons formally
Common Usage Patterns
Academic/Professional Writing
Formal explanations:
- 연구가 부족하기 때문에 더 조사해야 합니다 (Because research is insufficient, we must investigate more)
- 결과가 좋기 때문에 계속 진행합니다 (Because the results are good, we'll continue)
- 문제가 있기 때문에 수정이 필요합니다 (Because there's a problem, correction is needed)
News and Reports
Formal reporting:
- 날씨가 나쁘기 때문에 항공편이 지연되었습니다 (Because the weather is bad, flights are delayed)
- 경제가 좋지 않기 때문에 어려움이 있습니다 (Because the economy isn't good, there are difficulties)
Formal Announcements
Official statements:
- 공사 중이기 때문에 우회해 주세요 (Because of construction, please detour)
- 점검 중이기 때문에 이용할 수 없습니다 (Because of inspection, it's unavailable)
With Negative: -지 않기 때문에
Formal Negative Reason
Pattern: -지 않기 때문에
Examples:
- 좋지 않기 때문에 (because it's not good)
- 맞지 않기 때문에 (because it doesn't fit)
- 가능하지 않기 때문에 (because it's not possible)
Usage: Formal negative explanations
Shortened Form: 때문에
Noun + 때문에
With nouns directly:
- 시간 때문에 (because of time)
- 날씨 때문에 (because of weather)
- 일 때문에 (because of work)
- 당신 때문에 (because of you)
Note: When used with verbs/adjectives, must use -기
Contrast with Similar Forms
-기 때문에 vs -아/어서
-기 때문에: Formal, written (because)
- 바쁘기 때문에 못 갑니다 (Because I'm busy, I can't go)
- → Formal, official tone
-아/어서: Casual, spoken (because/so)
- 바빠서 못 가요 (I'm busy, so I can't go)
- → Natural, conversational
-기 때문에 vs -(으)니까
-기 때문에: Formal explanation (because)
- 중요하기 때문에 확인하세요 (Because it's important, please check)
- → Written, formal
-(으)니까: Natural spoken (since/because)
- 중요하니까 확인하세요 (It's important, so please check)
- → Spoken, more natural
When to Use Each
Use -기 때문에:
- Written documents
- Formal reports
- Academic papers
- Official announcements
- Business emails
Use -(으)니까 or -아/어서:
- Daily conversation
- Casual explanations
- Informal writing
- Text messages
- Spoken Korean
Example Sentences
Formal Writing
-
연구 결과가 신뢰할 수 있기 때문에 이 방법을 추천합니다
(Because the research results are reliable, we recommend this method) -
시간이 부족하기 때문에 계획을 수정해야 합니다
(Because time is insufficient, we must revise the plan) -
안전이 중요하기 때문에 규칙을 지켜야 합니다
(Because safety is important, rules must be followed)
News Reports
-
태풍이 접근하기 때문에 주의가 필요합니다
(Because a typhoon is approaching, caution is needed) -
경제가 악화되기 때문에 정책 변화가 예상됩니다
(Because the economy is worsening, policy changes are expected)
Business/Official
-
회의가 있기 때문에 참석해 주시기 바랍니다
(Because there's a meeting, please attend) -
시스템 점검이 있기 때문에 일시적으로 서비스가 중단됩니다
(Because of system inspection, service will be temporarily suspended)
Example Dialogues (Formal)
Dialogue 1: Business Email
Email: 일정이 변경되기 때문에 다시 확인해 주시기 바랍니다.
(Because the schedule has changed, please check again.)
Dialogue 2: Announcement
Announcement: 공사가 진행 중이기 때문에 소음이 있을 수 있습니다.
(Because construction is in progress, there may be noise.)
Dialogue 3: Academic
Paper: 데이터가 부족하기 때문에 추가 연구가 필요하다.
(Because data is insufficient, additional research is needed.)
Common Mistakes
❌ Incorrect: 가기 때문에요
Wrong casual ending
✅ Correct: 가기 때문입니다 or 가기 때문에
Use formal endings or no ending
❌ Incorrect: 바빠기 때문에
Double ㅂ
✅ Correct: 바쁘기 때문에
Keep original stem
❌ Incorrect: 날씨기 때문에
Missing -이 with noun
✅ Correct: 날씨 때문에 or 날씨이기 때문에
Noun + 때문에 or Noun + 이기 때문에
Casual Alternatives
How to Make It Less Formal
Instead of: 바쁘기 때문에 못 갑니다 Use:
- 바빠서 못 가요 (-아/어서 - casual)
- 바쁘니까 못 가요 (-(으)니까 - polite spoken)
-기 때문에 → Too formal for daily chat
With Different Sentence Types
Statements
- 중요하기 때문에 기억해야 합니다 (Because it's important, we must remember)
Commands
- 위험하기 때문에 조심하십시오 (Because it's dangerous, please be careful)
Questions (Rare)
- Rarely used in questions
- Better to use -(으)니까 or -아/어서
Summary Table
| Context | Formality | Better Choice |
|---|---|---|
| Daily conversation | Low | -아/어서, -(으)니까 |
| Polite conversation | Medium | -(으)니까 |
| Written reports | High | -기 때문에 ✓ |
| Academic papers | High | -기 때문에 ✓ |
| Business emails | High | -기 때문에 ✓ |
| Text messages | Low | -아/어서 |
Formality Comparison
| Expression | Formality | Usage |
|---|---|---|
| -기 때문에 | ★★★★★ | Written, formal |
| -(으)니까 | ★★★☆☆ | Spoken, polite |
| -아/어서 | ★★☆☆☆ | Spoken, casual |
Key Takeaways
✅ Formal reason expression: "Because" / "Due to"
✅ All verbs/adjectives: Just add -기 때문에
✅ Written Korean: Common in formal writing
✅ Not for daily speech: Too formal for conversation
✅ Use alternatives casually: -아/어서 or -(으)니까
✅ With nouns: Noun + 때문에 (without -기)
-기 때문에 is essential for formal Korean writing and official communication, but is rarely used in everyday casual conversation. For speaking, -(으)니까 or -아/어서 are much more natural choices.