# Bao lâu: how long (duration)? in Vietnamese (A1)

> Bao lâu asks how long something lasts. It goes after the verb, where the length of time will go in the answer: Anh ở Việt Nam bao lâu?

Source: https://vietnamesebuddy.com/grammar/bao-lau-how-long/ · Updated 2026-11-09

**how long (duration)?**

Pattern: `[person] + [verb] + (trong) + bao lâu?`

Level: A1 (our estimate) · Register: everyday

Typed without accents: bao lau

*Bao lâu* asks how long something lasts. It goes after the verb, where the length of time will go in the answer: *Anh ở Việt Nam bao lâu?* How long are you staying in Vietnam? *Anh ở hai tuần.* Two weeks.

You can put *trong* (for, within) in front, *trong bao lâu*, which sounds a little more careful. In everyday speech it's usually left out.

The answer is a number and a unit of time: *mười phút*, *hai tiếng* (two hours), *ba ngày*, *một tháng*. For a number of hours, say *tiếng*; *hai giờ* usually means two o'clock.

Four neighbors look alike. *Bao lâu nữa* asks how much longer until something happens, and often comes first: *Bao lâu nữa thì xong?* How much longer until it's done? *Bao lâu rồi* asks how long something has been going on, up to now: *Em học tiếng Việt bao lâu rồi?* *Mất bao lâu* asks how long a trip or a job takes: *Đi Vũng Tàu mất bao lâu?* And *khi nào*, or *bao giờ*, asks when, not how long.

## A common mistake

✗ Bao lâu anh ở Việt Nam?

✓ Anh ở Việt Nam bao lâu?

In a plain question, *bao lâu* goes where the answer goes, after the verb: *ở hai tuần*, so *ở bao lâu*.

## Examples

- Anh ở Việt Nam bao lâu? — How long are you staying in Vietnam?
- Anh ở hai tuần. — Two weeks.
- Mỗi ngày em học bao lâu? — How long do you study each day?
- Dạ, khoảng một tiếng. — About an hour.

## Words in this pattern

- [bao lâu](https://vietnamesebuddy.com/words/bao-lau/#lx_bao_lau): how long

## Compare

- [When? bao giờ / khi nào: first for the future, last for the past](https://vietnamesebuddy.com/grammar/bao-gio-when/): when?
- [For how long so far: … (bao lâu) rồi](https://vietnamesebuddy.com/grammar/duration-roi/): have been … for
- [It takes (time): mất](https://vietnamesebuddy.com/grammar/mat-time-takes/): it takes …

Previous in Asking questions: [How far: A cách B …, bao xa?](https://vietnamesebuddy.com/grammar/cach-distance/)
Next in Asking questions: [How many (a small number): mấy before the noun](https://vietnamesebuddy.com/grammar/may-how-many/)

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