Because of - Formal

The pattern -기 때문에 is used to express a clear, logical reason for a situation or action. It translates to "because" or "due to the fact that..." and places a stronger emphasis on the cause-and-effect relationship than other similar patterns.

Formation

It attaches directly to the stem of verbs and adjectives. For nouns, you use -(이)기 때문에.

Verb/Adjective Stem + -기 때문에

오다 (to come) → 오기 때문에 (because it's coming/raining)

비싸다 (to be expensive) → 비싸기 때문에 (because it's expensive)

Noun + -(이)기 때문에

학생 (student) → 학생이기 때문에 (because I am a student)

주말 (weekend) → 주말이기 때문에 (because it's the weekend)

Past Tense: Stem + -았/었기 때문에

늦다 (to be late) → 늦었기 때문에 (because I was late)

운동하다 (to exercise) → 운동했기 때문에 (because I exercised)

비가 오기 때문에 취소됐어요. / 학생이기 때문에 돈이 없어요. / 늦었기 때문에 못 들어가요.

While both patterns mean "because," they have important differences in nuance and grammar.

Nuance

-기 때문에: More objective and logical. It explicitly states the reason. It can sound slightly more formal or emphatic than -(아/어)서.

-(아/어)서: Implies a natural, sequential flow between the reason and the result. It's very common in everyday conversation and feels a bit softer.

Grammatical Restrictions

This is the most critical difference. Unlike -(아/어)서, the -기 때문에 pattern can be followed by commands, suggestions, and proposals.

Command:

위험하기 때문에 가지 마세요. (Correct)

위험해서 가지 마세요. (Incorrect - 위험하니까 would be used instead)

Statement:

비가 오기 때문에 길이 막혀요. (Correct - logical reason)

비가 와서 길이 막혀요. (Correct - natural flow, more common in speech)

Choose -기 때문에 when you need to give a clear justification, especially for a command or a strong suggestion.

중요하기 때문에 메모했어요. / 위험하기 때문에 가지 마세요. / 아프기 때문에 못 갔어요.

Learners are often taught that -기 때문에 is for formal situations or writing. While true, this can be misleading. It's frequently used in everyday speech when a speaker wants to state a reason with clarity and conviction.

Think of it as answering the question "Why?" in a very direct way. It's like presenting a clear piece of evidence for your action or feeling.

Situation 1: Explaining a decision.

좋아하기 때문에 샀어요. (I bought it because I like it.) This is a straightforward justification for the purchase.

Situation 2: Stating a personal feeling's cause.

너랑 있기 때문에 행복해. (I'm happy because I'm with you.) This emphasizes that 'being with you' is the specific, direct cause of the happiness.

So, don't reserve it only for essays. Use it in conversation whenever you want to make the reason for something crystal clear.

좋아하기 때문에 샀어요. / 운동했기 때문에 피곤해요. / 너랑 있기 때문에 행복해. / 건강하고 싶기 때문에 운동해요.

The -기 때문에 clause itself is neutral in terms of politeness. The formality of the entire sentence is determined by the final verb ending.

This pattern is flexible and appears in both casual speech (반말) and standard polite speech (해요체).

Casual Speech (반말)

Used with friends, family, or those younger than you. The sentence often ends in -아/어, -거야, or a plain command form.

사랑하기 때문에 헤어지는 거야. (I'm breaking up with you because I love you.)

위험하기 때문에 가지 마. (Don't go because it's dangerous.)

Polite Speech (해요체)

Used in most everyday situations with adults. The sentence ends in -아요/어요 or -세요.

사랑하기 때문에 헤어지는 거예요. (I'm breaking up with you because I love you.)

위험하기 때문에 가지 마세요. (Please don't go because it's dangerous.)

바빴기 때문에 못 만났어. / 바빴기 때문에 못 만났어요. / 춥기 때문에 코트를 입었어. / 춥기 때문에 코트를 입었어요.