因为 ... 所以 ... / 因为 alone
Reach for this when you want to spell out a cause and its result. The full 因为...所以... pair is the careful, written version — 'because X, therefore Y' — and is what beginners learn first. In real speech, Chinese speakers happily drop either half: just 因为 explains why; just 所以 delivers the conclusion. Both halves are correct; learners just need to know when to use which.
Structure
因为 [REASON]，所以 [RESULT] / 因为 [REASON]，[RESULT] / [REASON]，所以 [RESULT]
yīnwèi ..., suǒyǐ ...
How to Think About It
Unlike English, where 'because' and 'so' compete for the same slot, Chinese keeps BOTH because they mark different boundaries — 因为 flags the start of the reason, 所以 flags the start of the result. Dropping one is a stylistic shortcut, not an error: in conversation you usually keep whichever half points toward the part you want the listener to focus on. Keep 所以 when the result is the punch line; keep 因为 when the reason is the news.
Examples
因为今天下雨，所以我们不出门了。
yīnwèi jīntiān xià yǔ, suǒyǐ wǒmen bù chū mén le.
Because it's raining today, we're not going out.
因为他昨晚没睡好，整天没精神。
yīnwèi tā zuó wǎn méi shuì hǎo, zhěng tiān méi jīngshén.
Because he didn't sleep well last night, he was tired all day.
票太贵了，所以我没去看演唱会。
piào tài guì le, suǒyǐ wǒ méi qù kàn yǎnchànghuì.
The tickets were too expensive, so I didn't go to the concert.
Common Mistake
Learners over-correct after hearing native speakers drop a half and start dropping both — leaving the cause-effect link implicit. Without at least one of 因为 or 所以, the sentence reads as two unrelated facts side by side, and the listener has to guess at the connection.
我累了，我去睡觉了。
因为我累了，所以我去睡觉了。
Don't Confuse With
由于...因此...
Same meaning, much more formal. Use 由于/因此 in news articles, essays, and reports — not in spoken Chinese.
之所以...是因为...
Inverted version. Use this when you want to LEAD with the result and reveal the reason after — like 'the reason X is because Y.' 因为...所以... goes cause first; 之所以...是因为... goes result first.
...，因为...
This is the colloquial post-positioned 因为 — state the result, then tag on the reason. Common in casual speech. 因为...所以... is the careful, balanced version.
Practice
Fill the blank: ____今天太忙了，所以我没回你的消息。
Show answer
因为
Fill the blank: 因为他生病了，____今天没来上班。
Show answer
所以
Arrange: 没吃 / 因为 / 早饭 / 现在 / 我 / 很饿 / ，所以
Show answer
因为我没吃早饭，所以现在很饿。
Translate to Chinese: Because the traffic was bad, I was late.
Show answer
因为堵车，所以我迟到了。
Write a sentence explaining a decision using 因为 and 所以.
Show answer
因为我想多陪家人，所以我决定换工作。
Hear It in Real Episodes
This pattern appears in 1 Fluentide episode: