bao nhiêu vs mấy — Asking 'How Many' at Different Scales

Quick Answer

Both bao nhiêu and mấy translate to 'how many' or 'how much' in English, but they are used in different contexts. Bao nhiêu is generally for larger, unknown, or potentially numerous quantities, or when asking for a precise count in a general context.

Mấy is used for smaller, expected quantities, typically implying a number under ten or a 'few,' and is often more informal.

Comparison Table

Detailed Explanation

The choice between bao nhiêu and mấy hinges on the expected scale of the answer and the formality of the situation. While both ask about quantity, they carry different implications.

When to use bao nhiêu

Use bao nhiêu when you expect the quantity to be large, are genuinely unsure of the scale, or when asking in a more formal or general context. It is suitable for asking about things that could be numerous, such as the population of a city, the number of items in a large inventory, or the total cost of something when the price is entirely unknown. It implies you are looking for a specific, often exact, numerical answer, regardless of its size.

Bao nhiêu is also universally used for asking about prices: Bao nhiêu tiền? (How much money?) or Cái này giá bao nhiêu? (How much does this cost?).

When to use mấy

Use mấy when you expect the quantity to be small, typically under 10, or occasionally up to 20 for things like age. It's more informal and is commonly used in everyday conversations. For instance, when asking about the number of family members, small items purchased, or the age of a child, mấy is the natural choice. It conveys an expectation of a limited, countable number.

An important distinction is that mấy can also function as an indefinite quantifier meaning 'a few' or 'several' when not used in a question. For example, Tôi có mấy cuốn sách means 'I have a few books.'

Example Pairs

Common Patterns

Here are some fixed patterns where one word is typically preferred or required:

Asking for Price: Always use bao nhiêu.

Cái này giá bao nhiêu?

How much is this?

Asking for Age (especially for children or informally): Often use mấy.

Cháu mấy tuổi rồi?

How old is the child?

Time Duration (expected short term): Use mấy.

Bạn ở đây mấy tuần?

How many weeks will you stay here?

General Measurements (kilometers, kilograms, meters): Usually bao nhiêu, unless specifying a small, known quantity.

Quãng đường đó dài bao nhiêu km?

How many kilometers long is that road?

As 'a few/several' (non-question): Only mấy can be used this way.

Tôi có mấy người bạn Việt Nam.

I have a few Vietnamese friends.

Common Mistakes

Mistake 1 — Using 'mấy' for very large or general quantities

Using mấy when referring to quantities that are clearly numerous or completely unknown can sound awkward or incorrect, as it implies an expectation of a small number.

❌ Thành phố Hồ Chí Minh có mấy triệu dân?

✅ Thành phố Hồ Chí Minh có bao nhiêu triệu dân?

The population of Ho Chi Minh City is in the millions, a clearly large and generally unknown number for most people. Using mấy implies you expect a small number, which is inappropriate here. Bao nhiêu is correct for large, general quantities.

Mistake 2 — Using 'bao nhiêu' for very small, expected quantities

While not strictly incorrect, using bao nhiêu for items where a small quantity is expected can sound overly formal, distant, or imply a lack of awareness about common expectations.

❌ Bạn có bao nhiêu chiếc bút chì?

✅ Bạn có mấy chiếc bút chì?

For common stationery items like pencils, one usually expects a small, manageable number. Using bao nhiêu here makes it sound like you're asking about an inventory or a surprisingly large collection. Mấy is more natural and informal for such small, everyday quantities.

Mistake 3 — Confusing 'mấy' as a question word with 'mấy' as 'a few'

Learners sometimes forget that mấy can also function as a statement, meaning 'a few' or 'several', not just 'how many'.

❌ Tôi có bao nhiêu cuốn sách.

✅ Tôi có mấy cuốn sách.

If you intend to say "I have a few books" (a statement, not a question), only mấy is correct. Bao nhiêu exclusively functions as a question word for quantity. Using bao nhiêu here turns the statement into an incomplete question.

Quick Quiz

Fill in the blank with bao nhiêu or mấy:

1. Còn _____ phút nữa là bắt đầu buổi họp?

Hint: Meetings usually start in a specific, relatively short time, often less than an hour.

2. Giá vé máy bay đi Sài Gòn là _____ tiền?

Hint: Asking for the price of a flight ticket, which can vary widely and is generally unknown.

3. Anh ấy có _____ đứa cháu?

Hint: For family members like grandchildren, one typically expects a relatively small number.