vì vậy

That Is Why

Level 3

Vì vậy literally translates to 'because of that'. It is used to introduce the result or consequence of whatever was just said, much like 'therefore', 'so', or 'consequently' in English.

How It Works

1. Meaning and Usage
Vì vậy explicitly links a cause to an effect. It carries a slightly formal or emphatic tone compared to the standard nên and the neutral, everyday cho nên. While common in formal writing, it is also used in spoken conversation when a speaker wants to strongly emphasize a logical conclusion.

2. Sentence Placement
Because it means 'because of that', it must come after the cause has been stated. You will typically see it starting a new sentence or following a comma:

Trời mưa to. Vì vậy, tôi ở nhà. (It rained heavily. Therefore, I stayed home.)

3. Compared to Similar Words

Nên: nên is a conjunction of result that tightly binds two clauses. While vì vậy is excellent for starting a brand-new sentence to refer back to a previous thought, it is also frequently used mid-sentence to connect clauses.
Vì thế / Do đó: Vì thế is virtually identical in meaning and register to vì vậy. However, do đó is noticeably more formal and heavily preferred in academic writing and technical reports.
Bởi vậy: Bởi vậy is an extremely common, direct synonym for vì vậy and can be used interchangeably in most contexts.

4. Emphatic Combinations
For added emphasis, especially in spoken arguments or speeches, speakers frequently combine these words into vì vậy cho nên or vì vậy nên to strongly highlight the result.

5. Important Note
Do not use vì vậy as an intensifier like the English 'so' (as in 'I am so happy'). It is strictly a conjunction of result. For intensifiers, use words like rất / lắm / quá.

Examples (4)

Trời mưa to, vì vậy chuyến đi bị hoãn.
It rained heavily, therefore the trip was postponed.
Word by Word: Sky rain big, because thus trip go suffer postpone.
Here, 'vì vậy' follows a comma to introduce the logical consequence of the heavy rain.
Anh ấy bị ốm. Vì vậy, anh ấy sẽ không đến.
He is sick. For that reason, he will not come.
Word by Word: He suffer sick. Because thus, he will not arrive.
It is very common to use 'vì vậy' at the absolute beginning of a new sentence to refer back to the previous sentence.
Sinh con bình thường là một quá trình tự nhiên, vì vậy không cần phải sợ hãi.
Normal childbirth is a natural process, therefore there's no need to be scared.
Word by Word: Give birth child normal is one process natural, because thus not need must fear.
A slightly more formal example showing how 'vì vậy' connects a premise to a logical conclusion.
Đường phố rất đông đúc, vì vậy chúng tôi đến muộn.
The streets were very crowded, so we arrived late.
Word by Word: Street very crowded, because thus we arrive late.
While translated as 'so' here, it carries the weight of 'consequently'.

Common Mistakes

Using 'vì vậy' to mean 'because' (introducing the cause instead of the result).
Vì vậy trời mưa, tôi ở nhà.
Trời mưa, vì vậy tôi ở nhà.
Because 'vì vậy' contains the word vì (because), English speakers often mistakenly use it to introduce the reason. However, 'vì vậy' literally means 'because of THAT' (therefore) and must introduce the result. To say 'because', just use 'vì' or 'bởi vì'.
Creating a redundant pair by using 'vì' and 'vì vậy' in the same sentence.
Vì trời mưa, vì vậy tôi ở nhà.
Vì trời mưa nên tôi ở nhà.
Vietnamese frequently pairs conjunctions, but pairing 'vì' with 'vì vậy' is clunky and redundant because the word 'vì' is repeated. The correct pairing for a single sentence is vì ... nên ....

How It Connects

Tap a pattern to see what it builds on and what it leads to.

vì vậyLevel 3That Is Why

Learn This First

To understand 'vì vậy' (that is why / therefore), learners need to be familiar with the causal marker 'vì' (because) and the demonstrative 'vậy' (so/that). It is also helpful to understand the standard 'vì... nên...' structure, as 'vì vậy' serves a similar logical function but connects independent clauses.

Words in This Pattern