trước khi

Before (Doing)

Level 2

Trước khi means 'before' and is used directly in front of a verb or a full clause to show the chronological order of events.

How It Works

1. How to use it
Place trước khi directly before a verb phrase or a complete clause. The words attached to it do not change form.

  • Before a verb: Trước khi đi ngủ... (Before going to sleep...)
  • Before a clause: Trước khi trời mưa... (Before it rains...)

2. Clause placement
The trước khi clause can be placed at the beginning or the end of the sentence. When placed at the beginning, it is usually followed by a comma. A very natural and common structure is also to place the main subject before the trước khi clause.

  • Trước khi trời mưa, tôi sẽ về nhà. (Before it rains, I will go home.)
  • Tôi sẽ về nhà trước khi trời mưa. (I will go home before it rains.)
  • Tôi trước khi đi ngủ thường đọc sách. (Before going to sleep, I usually read books.)

3. Dropping the subject
If the person doing the action is the same in both parts of the sentence, Vietnamese naturally prefers dropping the subject in the trước khi clause.

4. Time markers are optional
A common myth is that you must use time markers like đã or sẽ to clarify when things happened. In reality, trước khi already establishes the timeline. Native speakers frequently omit time markers entirely, relying on context.

5. Important Distinctions

  • Use trước khi before verbs and clauses.
  • Use just trước before nouns (e.g., trước bữa ăn - before the meal) or for physical locations.
  • Use trước đây to mean 'previously' or 'in the past' as a standalone adverb.
  • Use [Time duration] + trước to express 'ago' (e.g., hai năm trước - two years ago). See Duration + trước.

6. Synonyms and Intensifiers

  • Trước lúc: A highly common synonym that is frequently used interchangeably with trước khi in everyday speech.
  • Ngay trước khi: Means 'right before' or 'just before', used to express that an action happened immediately before another (e.g., Tôi đến ngay trước khi phim bắt đầu. - I arrived right before the movie started).

Examples (4)

  1. Trước khi đi ngủ, tôi đọc sách.

    Before going to bed, I read a book.

    Word by Word: Before time go sleep, I read book.

    Notice how the subject 'tôi' (I) is omitted in the first clause because it is the same as the subject in the main clause.

  2. Tôi sẽ sửa cửa sổ trước khi trời mưa.

    I will fix the window before it rains.

    Word by Word: I will fix window before time sky rain.

    Here, 'trước khi' is followed by a full clause ('trời mưa' - the sky rains).

  3. Trước khi đến Việt Nam, tôi đã học tiếng Việt.

    Before coming to Vietnam, I studied Vietnamese.

    Word by Word: Before time arrive Vietnam, I past-marker study language Vietnamese.

    The conjunction establishes the timeline, making it clear that the studying happened first.

  4. Nhớ rửa tay trước khi ăn.

    Remember to wash your hands before eating.

    Word by Word: Remember wash hand before time eat.

    A very common everyday instruction. 'Trước khi' attaches directly to the verb 'ăn'.

Common Mistakes

  • Omitting 'khi' before a verb.

    Trước đi ngủ, tôi đọc sách.
    Trước khi đi ngủ, tôi đọc sách.

    English speakers often translate 'before + verb' literally using just 'trước'. However, 'trước' alone is a preposition for nouns or locations. When followed by a verb or clause, you must use 'trước khi'.

  • Repeating the subject unnecessarily.

    Trước khi tôi đi ngủ, tôi đọc sách.
    Trước khi đi ngủ, tôi đọc sách.

    Because English requires a subject in both clauses, learners often repeat the pronoun. In Vietnamese, if the subject is the same, it is naturally and preferably omitted in the dependent clause.

How It Connects

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

trước khiLevel 2Before (Doing)

Learn This First

To understand 'trước khi' (before), learners first need to be familiar with the word 'khi' (when) which forms the basis of temporal markers. They should also understand that Vietnamese verbs remain in their base form regardless of the time context, and have a grasp of basic word order to correctly position the temporal clause relative to the main action.

Words in This Pattern

trước khi