bao nhiêu

In Vietnamese, question words stay in place. Because of this, bao nhiêu simply stays attached to the noun it modifies. If the noun is the subject, it appears at the front (Bao nhiêu người đến? - How many people are coming?). If the noun is the object, it appears later in the sentence (Bạn muốn mua bao nhiêu quả táo? - How many apples do you want to buy?). When asking for a price, it acts as the predicate (Cái này bao nhiêu tiền? - How much is this?). Note that when the context is clear, the noun is often dropped entirely (e.g., Cái này bao nhiêu? is just as common for asking a price).

1. With Nouns:
For uncountable nouns (like money), attach it directly before the noun.
• bao nhiêu tiền (how much money)
For many physical countable objects, you usually need a classifier between bao nhiêu and the noun.
• bao nhiêu quả táo (how many apples)
Importantly, certain common countable nouns (like người, ngày, tuổi), units of measurement (like mét, lít, ký), and units of time (like giờ, phút) act as their own classifiers. These attach directly to bao nhiêu without an extra word.
• bao nhiêu tuổi (how many years of age)
• bao nhiêu ký (how many kilos)
However, if you are treating a countable object as a mass or ingredient (e.g., how much apple goes into a smoothie), you can drop the classifier and just say bao nhiêu táo.

2. With Adjectives:
When asking 'how + adjective', bao nhiêu typically follows the adjective.
• cao bao nhiêu (how tall)
• nặng bao nhiêu (how heavy)
Related Structure: The interrogative adverb bao can also be used directly with adjectives for measurements as a standard structure, such as bao lâu (how long), bao xa (how far), or bao lớn (how big).

3. With Verbs:
When asking about the quantity or extent of an action, bao nhiêu goes after the verb.
• Bạn muốn mua bao nhiêu? (How much do you want to buy?)

4. Bao nhiêu vs. Mấy:
Use mấy when you expect a small number (traditionally under 10). Use bao nhiêu for large numbers, uncountable nouns, or when you simply don't know. Just like with bao nhiêu, you usually use a classifier with mấy for physical countable objects (e.g., mấy quả táo). For example, when asking someone's age, use mấy tuổi for children (under 10) and bao nhiêu tuổi for adults.

5. Asking about Sequences and Numbers:
When asking about items in a sequence or identification numbers, use mấy for smaller numbers or general sequences (e.g., Tập mấy? - Which episode?, Xe buýt số mấy? - Which bus number?). However, for large identification numbers like phone numbers or bank accounts, bao nhiêu is perfectly natural and often preferred.
• Số điện thoại của bạn là bao nhiêu? (What is your phone number?)

6. Asking the Date and Time:
When asking for the time on the clock, always use mấy giờ (What time is it?). If you use bao nhiêu giờ or bao nhiêu tiếng, it changes the meaning to ask about a duration (How many hours?). When asking for the day of the month, use mùng mấy for the 1st through the 10th. For the 11th onwards, you can use ngày bao nhiêu, though native speakers frequently use ngày mấy for any date of the month. For other time units: always use thứ mấy for days of the week and tháng mấy for months (even though there are 12 months). For years, use năm bao nhiêu or năm nào.

7. As an Indefinite Pronoun and Exclamation:
Bao nhiêu isn't just for questions. In statements, it can mean "any amount" or "however much" (e.g., Bao nhiêu cũng được - Any amount is fine). When used with a negative, không... bao nhiêu means "not much" (e.g., Tôi kiếm được không bao nhiêu tiền - I don't earn much money). It is also used in exclamations of large quantities, such as biết bao nhiêu or bao nhiêu là (so many / so much). Finally, it pairs with bấy nhiêu in the correlative structure bao nhiêu ... bấy nhiêu (as much... that much).