왜냐하면 vs 때문에: Differences in Expressing Reasons

왜냐하면 (wae-nya-ha-myeon, waenyahamyeon) · 때문에 (ttae-mun-e, ttaemune)

왜냐하면 is mainly used at the beginning of a sentence to explain reasons, while 때문에 attaches after a noun to indicate cause or reason.

Comparison of Korean conjunctions 왜냐하면 and 때문에 for expressing reasons

Word-by-word breakdown

One lane per word — no nested boxes, just the gist.

왜냐하면(wae-nya-ha-myeon, waenyahamyeon)

A conjunctive adverb used to explain reasons

When to use

Reason at sentence start, Presenting logical grounds, Detailed reason in spoken Korean

The nuance

왜냐하면 is used at the beginning or middle of a sentence to explain reasons in detail and is usually followed by a complete sentence.

때문에(ttae-mun-e, ttaemune)

A postpositional particle and conjunction indicating cause or reason

When to use

Cause after noun, Explaining result, Formal sentence structure

The nuance

때문에 attaches after a noun to indicate cause or reason and is mainly used in the middle or end of sentences.

Real-world examples

  • 나는 피곤해. 왜냐하면 어제 늦게 잤어.

    na-neun pi-gon-hae. wae-nya-ha-myeon eo-je neuj-ge jass-eo., na neun pi gon hae. wae nya ha myeon eo je neuj ge jass eo.

    Because 왜냐하면 is followed by a complete sentence, it sounds natural.

  • 나는 피곤해. 때문에 어제 늦게 잤어.

    na-neun pi-gon-hae. ttae-mun-e eo-je neuj-ge jass-eo., na neun pi gon hae. ttae mun e eo je neuj ge jass eo.

    때문에 must attach to a noun; using it at the sentence start is unnatural.

  • 지각했어. 교통 체증 때문에.

    ji-gak-haess-eo. gyo-tong che-jeung ttae-mun-e., ji gak haess eo. gyo tong che jeung ttae mun e.

    때문에 attaches after a noun and can be used at sentence end to indicate cause.

  • 지각했어. 왜냐하면 교통 체증.

    ji-gak-haess-eo. wae-nya-ha-myeon gyo-tong che-jeung., ji gak haess eo. wae nya ha myeon gyo tong che jeung.

    왜냐하면 must be followed by a full sentence, so just a noun is incorrect.

  • 회의가 취소되었어요. 왜냐하면 사장님이 아프셔서요.

    hoe-ui-ga chwi-so-doe-eoss-eo-yo. wae-nya-ha-myeon sa-jang-nim-i a-peu-syeo-seo-yo., hoe ui ga chwi so doe eoss eo yo. wae nya ha myeon sa jang nim i a peu syeo seo yo.

    A complete sentence explaining the reason follows 왜냐하면, making it natural.

  • 시험을 못 봤어요. 왜냐하면 공부를 안 했어요.

    si-heom-eul mos bwass-eo-yo. wae-nya-ha-myeon gong-bu-reul an haess-eo-yo., si heom eul mos bwass eo yo. wae nya ha myeon gong bu reul an haess eo yo.

    왜냐하면 is correctly followed by a full reason sentence.

  • 시험을 못 봤어요. 공부 안 했기 때문에.

    si-heom-eul mos bwass-eo-yo. gong-bu an haess-gi ttae-mun-e., si heom eul mos bwass eo yo. gong bu an haess gi ttae mun e.

    때문에 correctly attaches after a noun phrase indicating cause.

Quick quiz

  1. Which sentence correctly uses '왜냐하면'?

    다음 중 ‘왜냐하면’을 올바르게 사용한 문장은?(da-eumjung‘wae-nya-ha-myeon’eulol-ba-reu-gesa-yong-hanmun-jang-eun?, daeumjung‘waenyahamyeon’eulolbareugesayonghanmunjangeun?)
  2. Which sentence correctly uses '때문에'?

    ‘때문에’를 올바르게 사용한 문장은?(‘ttae-mun-e’reulol-ba-reu-gesa-yong-hanmun-jang-eun?, ‘ttaemune’reulolbareugesayonghanmunjangeun?)
  3. Which is used at the beginning of a sentence to explain reasons in detail?

    ‘왜냐하면’과 ‘때문에’ 중 문장 앞에서 이유를 자세히 설명할 때 쓰이는 것은?(‘wae-nya-ha-myeon’gwa‘ttae-mun-e’jungmun-jangap-e-seoi-yu-reulja-se-hiseol-myeong-halttaesseu-i-neungeos-eun?, ‘waenyahamyeon’gwa‘ttaemune’jungmunjangapeseoiyureuljasehiseolmyeonghalttaesseuineungeoseun?)

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