In Vietnamese, we use bao nhiêu and thế nào to ask about degrees, like “how” in English.
Basic structure
Structure
Place bao nhiêu or thế nào after an adjective to ask about degrees.
adj. + bao nhiêu / thế nào
Regarding usage, use bao nhiêu with adjectives that indicate a measurable property, like “three metres (long)” or “five kilograms (heavy)”. For immeasurable properties, use thế nào.
Examples
- dài bao nhiêu
how long - sâu bao nhiêu
how deep - mệt thế nào
how tired - tài năng thế nào
how talented
Exceptions
There are three exceptions to the general structure above: nhiều (“many/much”), xa (“far”), and lâu (“long”, in “long time”, not “long distance”). These three adjectives go with bao only.
Structure
Place bao before nhiều, lâu, or xa. In this structure, nhiều (fourth tone) has its tone changed (to first tone), becoming nhiêu. This is mandatory, so saying bao nhiều is wrong.
bao + nhiêu / lâu / xa
Examples
- bao xa
how far
Extended structure
We can specify the unit of measurement in the question, like “how many kilograms heavy” instead of “how heavy”. It’s a hybrid of the basic structure and the structure of asking about quantities.
Structure
Add a unit of measurement after bao nhiêu.
adj. + bao nhiêu + unit of measurement
As a rule, if the answer is expected to be less than ten, we can (and should) replace bao nhiêu with mấy.
adj. + mấy + unit of measurement
Examples
- dài bao nhiêu mét
how many metres long - nặng mấy tấn
how many tonnes heavy
Asking “how often”
There are no straightforward ways to ask “how often” in Vietnamese, but we can work around it by rephrasing with bao lâu (“how long”), một lần (“once”), and bao nhiêu lần (“how many times”).
Structure
Place bao lâu before and một lần after a verb (plus its object, if there is one) to ask how long it takes for something to occur once:
bao lâu + verb (+ obj.) + một lần
Place một plus a unit of time before and bao nhiêu lần after a verb (plus its object, if there is one) to ask how many times something occurs per unit of time:
một + unit of time + verb (+ obj.) + bao nhiêu lần
We can move một plus the unit of time after bao nhiêu lần.
verb (+ obj.) + bao nhiêu lần + một + unit of time
Alternatively, we can use mỗi (“each”) instead of một, but it’s less common.
mỗi + unit of time + verb (+ obj.) + bao nhiêu lần
verb (+ obj.) + bao nhiêu lần + mỗi + unit of time
Examples
- Năm nhuận bao lâu có một lần
How often are leap years?How long does it take for a leap year to occur? - một ngày đánh răng bao nhiêu lần
How often to brush?How many times to brush a day?
Usage notes
If you place mỗi lần before and bao lâu after a verb (plus its object, if there is one), it won’t mean “how often”, but rather “how long each occurence of something lasts”.
Structure
mỗi lần + verb (+ obj.) + bao lâu
Examples
- mỗi lần đánh răng bao lâu
How long to brush?
- bao lâu đánh răng một lần
How often to brush?