bao lâu

How Long

Level 1

Bao lâu means how long. It is the standard way to ask about the duration of an action or state.

How It Works

In Vietnamese, asking about duration is simple. You use the phrase bao lâu, but its position and the words you pair it with depend on the timeframe:

1. Past up to Present (How long have you...)
Place bao lâu rồi at the end of the sentence. Native speakers often add đã before the verb and được before bao lâu.
Structure: Subject + [đã] + Verb + [Object] + [được] + bao lâu rồi?
Example: Bạn đã học tiếng Việt được bao lâu rồi? (How long have you been studying Vietnamese?)

2. General, Future, or Completed Past Duration
Place bao lâu at the end of the sentence. For completed past actions, use bao lâu at the end without rồi.
Structure: Subject + Verb + [Object] + bao lâu?
Example: Bạn sẽ ở đây bao lâu? (How long will you stay here?)

3. Future Countdown (How much longer until...)
Use bao lâu nữa thì. While it often goes at the beginning of the sentence, the subject can also naturally precede it. Native speakers heavily rely on còn (still/remaining) to emphasize the remaining time.
Structure: [Còn] + bao lâu nữa thì + Action? OR [Subject] + [còn] + bao lâu nữa thì + Action?
Example: Xe buýt còn bao lâu nữa thì đến? (How much longer until the bus arrives?)

4. Continuing Duration (How much longer will you...)
Place bao lâu nữa (without thì) at the end of the sentence to ask how much longer an ongoing action will continue. You will often hear còn before the verb.
Structure: Subject + [còn] + Verb + [Object] + bao lâu nữa?
Example: Bạn sẽ còn ở đây bao lâu nữa? (How much longer will you stay here?)

5. Time Required (How long does it take...)
Use mất bao lâu to ask about the time required to complete an action or travel.
Structure: Action + mất bao lâu? OR Mất bao lâu để + Action?
Example: Đi đến đó mất bao lâu? (How long does it take to get there?)

6. Frequency (How often...)
Use bao lâu ... một lần to ask how often something happens.
Structure: [Subject] + Action + bao lâu một lần?
Example: Bạn đi du lịch bao lâu một lần? (How often do you travel?)

7. Answering bao lâu Questions
To answer, simply replace bao lâu with the specific time duration, keeping the rest of the sentence structure intact. If the question uses được before bao lâu, keep it in the answer to mean 'for [duration]'.
Examples:
- Bạn sẽ ở đây bao lâu? → Tôi sẽ ở đây 3 ngày. (I will stay here for 3 days.)
- Bạn đã học được bao lâu rồi? → Tôi đã học được 2 năm rồi. (I have studied for 2 years.)

8. Non-Question Usages
Bao lâu is also frequently used in statements to mean 'a long time' or 'not long'.
Examples: bao lâu nay (for a long time now), không bao lâu nữa (soon / not much longer).

Note: Do not confuse bao lâu (duration) with bao giờ or khi nào (point in time).

Examples (6)

  1. Bạn đã học tiếng Việt được bao lâu rồi?

    How long have you been studying Vietnamese?

    Word by Word: You past-marker study Vietnamese get how long already?

    Adding 'được' before 'bao lâu' and 'rồi' at the end is the most natural way to ask about an action that started in the past and continues to the present.

  2. Bạn sẽ ở Việt Nam bao lâu?

    How long will you stay in Vietnam?

    Word by Word: You will stay in Vietnam how long?

    For general or future duration, 'bao lâu' sits at the end of the sentence.

  3. Anh ấy đã ngủ bao lâu?

    How long did he sleep?

    Word by Word: He past-marker sleep how long?

    For a completed action in the past, 'bao lâu' stays at the end without 'rồi'.

  4. Xe buýt còn bao lâu nữa thì đến?

    How much longer until the bus arrives?

    Word by Word: Bus still how long more then arrive?

    When asking 'how much longer until' a future event, 'bao lâu nữa thì' is used. Adding 'còn' (still/remaining) makes it highly natural.

  5. Đi đến đó mất bao lâu?

    How long does it take to get there?

    Word by Word: Go arrive there lose how long?

    Use 'mất bao lâu' to ask about the amount of time required to complete an action or a journey.

  6. Bạn đi du lịch bao lâu một lần?

    How often do you travel?

    Word by Word: You go travel how long one time?

    The phrase 'bao lâu ... một lần' is the standard way to ask 'how often' an action occurs.

Common Mistakes

  • Putting 'bao lâu' at the beginning of the sentence for past or present duration.

    Bao lâu bạn học tiếng Việt?
    Bạn học tiếng Việt bao lâu rồi?

    English speakers often put 'how long' at the beginning of the sentence. In Vietnamese, for past or present duration, 'bao lâu' usually goes at the end, together with 'rồi'.

  • Leaving out 'rồi' when asking 'how long have you been doing something'.

    Different MeaningBạn sống ở đây bao lâu?
    Bạn sống ở đây bao lâu rồi?

    'Bạn sống ở đây bao lâu?' is a correct sentence, but without the final particle 'rồi' (already) it often asks how long you plan to stay, or how long in total. Add 'rồi' to ask how long you have been living here until now.

How It Connects

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

bao lâuLevel 1How Long

Learn This First

To understand 'bao lâu' (how long), learners need to be familiar with basic Vietnamese word order and the use of 'bao' as an interrogative prefix for time-related questions.

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Patterns that build on this one.

Words in This Pattern

bao lâulâubao