Numbers and Time in Vietnamese

In Brief

Vietnamese builds numbers regularly: 21 is hai mươi mốt (“two tens and one”), and 35 is ba mươi lăm. To ask the time, say Bây giờ mấy giờ?; answer with a number plus giờ, as in ba giờ chiều. For prices, put đồng after the amount and ask Bao nhiêu tiền? or Giá bao nhiêu?

Overview

Numbers are an essential A1 skill: you need them for phone numbers, quantities, ages, addresses, times, and prices. The basic Vietnamese system is quite regular. Once you know the words from zero to ten, you can construct nearly every number up to 100. A few digits change form in certain positions, especially one, four, and five.

Vietnamese number words do not change for singular or plural. However, when you count objects, the number commonly comes before a classifier (a counting word used with a category of nouns): ba con chó means “three dogs,” while hai cuốn sách means “two books.” This article concentrates on the numbers themselves, clock time, and money; the related article on classifiers explains noun phrases in more detail.

Time and prices use the same number system but add practical words such as giờ “hour/o’clock,” phút “minute,” and đồng, the name of Vietnam’s currency. Unlike English, Vietnamese does not normally require “a.m.” or “p.m.”: a part-of-day word such as sáng or chiều usually makes the meaning clear.

How It Works

The basic numbers: 0–10

Number	Vietnamese	Approximate learner cue
0	không	also the ordinary word for “not/no”
1	một	base form of one
2	hai	two
3	ba	three
4	bốn	base form of four
5	năm	base form of five
6	sáu	six
7	bảy	seven
8	tám	eight
9	chín	nine
10	mười	ten

Vietnamese is a tonal language, so tone marks are part of the spelling, not decoration. For example, bảy and bay are not interchangeable. Learn each number aloud with its tone.

From 11 to 19

Use mười + unit:

Number	Formation	Vietnamese
11	10 + 1	mười một
12	10 + 2	mười hai
14	10 + 4	mười bốn
15	10 + modified 5	mười lăm
19	10 + 9	mười chín

The important exception is 15: final năm becomes lăm after a tens expression. In careful standard usage, 14 is mười bốn, not mười tư.

Multiples of ten and numbers up to 99

For 20, 30, and so on, use digit + mươi. Add the final unit when needed:

Number	Vietnamese	Literal structure
20	hai mươi	two tens
23	hai mươi ba	two tens three
30	ba mươi	three tens
42	bốn mươi hai	four tens two
68	sáu mươi tám	six tens eight
99	chín mươi chín	nine tens nine

Three common unit forms deserve special attention:

• mốt replaces một after a tens number greater than ten: 21 is hai mươi mốt, 31 is ba mươi mốt. But 11 remains mười một.
• lăm replaces năm after mười or mươi: 15 is mười lăm and 25 is hai mươi lăm.
• tư may replace bốn after mươi: 24 can be hai mươi tư. Hai mươi bốn is also correct and is often the safer beginner form. After plain mười, standard careful speech normally uses bốn: mười bốn.

The word for 100 is một trăm. This lesson’s core range ends there, but the same place-value logic continues beyond 100.

Numbers with nouns and classifiers

The usual counting pattern is:

number + classifier + noun

• ba người — three people (người functions as the people classifier)
• bốn con mèo — four cats
• năm cuốn sách — five books
• hai cái ghế — two chairs

English puts a number directly before most count nouns. Vietnamese often inserts a classifier, so translating “three + dogs” word for word as ba chó can sound incomplete or unnatural in ordinary neutral speech. Some measurements and time units combine directly with a number: hai giờ “two hours/two o’clock,” mười phút “ten minutes,” and ba đồng “three đồng.”

Asking and telling clock time

The basic question is:

Bây giờ mấy giờ? — What time is it now?

Here mấy asks for a number, usually from an expected, manageable range. To answer, use:

number + giờ + minutes + part of day

Not every piece is required. Compare:

• ba giờ — three o’clock
• ba giờ mười phút — 3:10
• ba giờ rưỡi — half past three
• ba giờ chiều — 3 p.m.
• ba giờ mười phút chiều — 3:10 p.m.

Phút means “minute.” In ordinary conversation it can be omitted when the context is clearly clock time: bảy giờ mười lăm means 7:15. Rưỡi means “and a half,” so it follows the unit: tám giờ rưỡi is 8:30.

To express minutes before the next hour, kém means “short of/to”:

• bốn giờ kém mười — ten to four (3:50)
• bảy giờ kém năm phút — five minutes to seven

For an A1 learner, saying the hour followed by the exact minutes is always a clear alternative: ba giờ năm mươi for 3:50.

Parts of the day

Vietnamese commonly disambiguates a 12-hour time with a word after the clock expression:

Vietnamese	General meaning	Example
sáng	morning	bảy giờ sáng — 7 a.m.
trưa	around noon	mười hai giờ trưa — 12 noon
chiều	afternoon	ba giờ chiều — 3 p.m.
tối	evening/night	tám giờ tối — 8 p.m.

The boundaries are based on how speakers view the part of the day, not on a rigid grammatical rule. At noon, mười hai giờ trưa is the clearest expression. Midnight is mười hai giờ đêm or không giờ in a 24-hour system.

When stating an appointment, the time can come before or after the action depending on emphasis, but a common pattern is time + subject + verb: Ba giờ chiều tôi đi làm (“At three in the afternoon, I go to work”). You can also say Tôi đi làm lúc ba giờ chiều, using lúc to mark the time at which something happens.

Asking about and stating prices

Two useful questions are:

• Bao nhiêu tiền? — How much money?/How much is it?
• Giá bao nhiêu? — What is the price?

For a specific item, say Cái này bao nhiêu tiền? (“How much is this?”) or Cái này giá bao nhiêu? The answer normally places the currency after the number:

number + đồng

For example, năm mươi nghìn đồng is 50,000 đồng. Although counting from 0 to 100 is the beginner target here, real prices in Vietnam quickly require nghìn “thousand.” In a shop, speakers often omit đồng when the currency is obvious: Năm mươi nghìn (“Fifty thousand”).

Do not copy English currency order. English can write “₫50,000,” but spoken Vietnamese says the amount first and đồng last.

Examples in Context

Vietnamese	English	Note
một, hai, ba, bốn, năm	one, two, three, four, five	Basic sequence
Lớp có hai mươi mốt người.	The class has twenty-one people.	mốt in final position
Tôi có mười lăm cuốn sách.	I have fifteen books.	Final five becomes lăm
Cô ấy mua hai mươi bốn cái bánh.	She buys twenty-four cakes.	bốn is correct; tư is also possible here
Bây giờ mấy giờ?	What time is it now?	Standard clock-time question
Bây giờ là chín giờ.	It is nine o’clock now.	là is natural but can be omitted in short answers
Chúng ta gặp nhau lúc mười giờ sáng.	We will meet at ten in the morning.	lúc introduces an event time
Tôi ăn trưa lúc mười hai giờ trưa.	I eat lunch at twelve noon.	Noon is made explicit
Phim bắt đầu lúc bảy giờ rưỡi tối.	The film starts at 7:30 p.m.	rưỡi means half past
Xe đến lúc sáu giờ mười lăm phút.	The vehicle arrives at 6:15.	Full hour-and-minute form
Bây giờ là bốn giờ kém mười.	It is ten to four now.	Literally “four hours short ten”
Cái này bao nhiêu tiền?	How much is this?	Everyday shopping question
Cà phê này hai mươi nghìn đồng.	This coffee is 20,000 đồng.	Currency follows the amount
Hai cái này giá bao nhiêu?	How much are these two?	Number + classifier + demonstrative

Common Mistakes

Using một after a larger tens number

• Wrong: hai mươi một
• Right: hai mươi mốt
• Why: Final “one” normally becomes mốt after hai mươi, ba mươi, and the other larger tens. Keep một in mười một (11).

Keeping năm in 15, 25, and similar numbers

• Wrong: hai mươi năm when you mean 25
• Right: hai mươi lăm
• Why: In the final unit position after a tens expression, five becomes lăm. Be careful: hai mươi năm can instead be understood as “twenty years,” because năm also means “year.”

Putting the part of day before the time

• Wrong: chiều ba giờ
• Right: ba giờ chiều
• Why: In a clock expression, Vietnamese normally puts sáng, trưa, chiều, or tối after the hour.

Copying English “half past” word order

• Wrong: rưỡi ba giờ
• Right: ba giờ rưỡi
• Why: Rưỡi follows the measured unit: literally “three hours and a half.”

Putting đồng before the amount

• Wrong: đồng năm mươi nghìn
• Right: năm mươi nghìn đồng
• Why: The spoken currency name follows the number in Vietnamese.

Using bao nhiêu giờ for every time question

• Wrong: Bây giờ bao nhiêu giờ? as the beginner default
• Right: Bây giờ mấy giờ?
• Why: Mấy giờ? is the standard everyday question for clock time. Bao nhiêu giờ? is often interpreted in contexts involving a number or duration of hours, so it is not the best phrase to memorize for “What time is it?”

Usage Notes

In everyday speech, short answers are common. To Mấy giờ rồi? (“What time is it already/now?”), someone may simply answer Ba giờ rưỡi without Bây giờ là. Likewise, shop staff and customers often leave out đồng when everyone knows the currency.

Vietnamese speakers may read strings digit by digit rather than as one whole number. Phone numbers are a clear example: each digit is normally said separately, and zero is không. In phone numbers and other digit strings, you may hear regional or colloquial variants, but beginners should use the standard forms in the main number table.

Both hai mươi bốn and hai mươi tư can mean 24. Preferences vary with rhythm, context, and speaker. Recognize tư, but using bốn consistently is accurate and easy. Similarly, natural connected speech may sound faster than the carefully separated forms shown in a table; the written structure does not change.

Beyond the Basics / Advanced Use

You do not need to master these details at A1, but they explain forms you will soon encounter.

Formal schedules, transport information, and announcements often use the 24-hour clock: mười lăm giờ is 15:00. In normal conversation, ba giờ chiều is more likely. Written times may appear with punctuation or an h, such as 15:30 or 15h30, while speech still uses giờ and optionally phút.

Above 100, Vietnamese continues with place-value words: trăm “hundred,” nghìn/ngàn “thousand,” and triệu “million.” Real prices therefore introduce larger numbers early. Northern usage strongly favors nghìn, while ngàn is common in the south; both mean “thousand.” A fuller treatment also needs the linking word lẻ/linh in numbers such as 105, but that is beyond the 0–100 core of this lesson.

The question words mấy and bao nhiêu overlap but are not identical. Mấy often expects a relatively small or conventional answer, as in mấy giờ; bao nhiêu asks “how much/how many” without the same expectation and is standard for prices. This is a usage tendency, not a mathematical limit: context determines what sounds natural.

Finally, giờ can mean either a clock hour or a duration unit. Hai giờ may mean “two o’clock” or “two hours.” A part-of-day phrase, the surrounding verb, or a duration marker resolves the meaning: lúc hai giờ chiều is “at 2 p.m.,” while trong hai giờ is “for two hours.”

Practice Tips

1. Build numbers instead of memorizing a long list. Choose a tens word, add a random digit, and say the result aloud. Give extra practice to numbers ending in 1 and 5: 21, 25, 31, 35, and so on.
2. Narrate your day with a clock. At several points each day, ask Bây giờ mấy giờ? and answer in Vietnamese. Alternate exact minutes, rưỡi, and a part-of-day word.
3. Turn prices into a listening drill. Read five realistic prices aloud, then write the digits from your own recording. Always say the amount before đồng, and practice both the full form and the natural shortened form without the currency word.

Related Concepts

• Prerequisite: Classifiers — explains the counting words in phrases such as ba con chó and năm cuốn sách.
• Next step: Basic Time Words — adds hôm nay, hôm qua, ngày mai, and parts of the day.
• Next step: Days, Months, and Dates — uses numbers to form calendar dates and talk about schedules.