tư

Four in Twenty-Four and Up

Level 1

In Vietnamese, the number 4 is usually bốn. But in certain situations—like saying 'Wednesday', 'April', or numbers from 24 upwards—you use tư instead.

How It Works

While bốn is the standard word for 'four', tư is a special variant used in specific contexts. For basic counting (e.g., bốn người - four people), always use bốn. As a beginner, focus on these essential rules:

1. Days of the Week & Ordinals: 'Wednesday' is always thứ tư. For ordinals ('fourth'), thứ tư is the standard (e.g., lần thứ tư - the fourth time).

2. Months & Dates: 'April' is standardly tháng tư (though tháng bốn is sometimes used colloquially). For the 4th day of the month, mùng bốn or ngày bốn is the universal standard. However, mùng tư is also used colloquially nationwide, particularly in paired phrases like mùng ba mùng tư.

3. Numbers 24 and Up: When 4 is the last digit of a number 20 or higher, both tư and bốn are standard, correct, and taught in textbooks (e.g., hai mươi tư or hai mươi bốn). In everyday speech, tư is heavily favored in the North, while bốn is heavily favored in the South and is often recommended as the safest standard for beginners to avoid ambiguity. It attaches to mươi (tens).

4. The Number 14 and Leading 4s: For counting and math, 14 is standardly mười bốn. However, mười tư is used for lunar calendar dates (e.g., ngày mười tư) and in some traditional phrases (e.g., trăng mười tư - the moon on the 14th). When 4 is the first digit of any unit (40, 400, 4,000), it is always bốn and never tư. For example, 44 combines these rules as bốn mươi tư (or bốn mươi bốn), but never tư mươi tư.

5. Fractions & Divisions: tư is used in fractions, such as một phần tư (one-fourth or a quarter). When dividing things, both tư and bốn are perfectly natural and correct, like chia làm tư or chia làm bốn (to divide into four), and cắt làm tư or cắt làm bốn (to cut into four).

6. Shorthand for Prices and Quantities: In everyday speech, trailing zeros are often dropped. For 140, both một trăm tư and một trăm bốn are used as shorthand. To say 104, you use a filler word and can use either bốn or tư: một trăm linh bốn / linh tư (North) and một trăm lẻ bốn / lẻ tư (South). Similarly, 1,400 is một ngàn tư.

7. Southern Kinship: In Southern Vietnam, Tư is used for the third-born child in a family (e.g., Anh Tư, Chị Tư). This is because the first-born is called Hai (Two) and the second-born is Ba (Three). You cannot use bốn here.

8. Telling Time: For 4 o'clock, always use bốn giờ, never tư giờ.

9. Common Vocabulary: A very common everyday word using tư is ngã tư (intersection or crossroads). You might also hear the idiom ngày tư ngày tết (the holidays / the Tet season). Note that the tư here does not mean 'four', but derives from a Sino-Vietnamese vocabulary word for 'season/order' (tiết tự).

Note: You may also encounter tứ, which is the Sino-Vietnamese vocabulary root for 4, used in fixed compound words like tứ giác (quadrilateral) or tứ kết (quarter-final). Additionally, be aware of the homophone tư meaning 'private' or 'personal' (e.g., công ty tư nhân - private company, riêng tư - private).

  • 14 = mười bốn (standard) or mười tư (lunar dates)
  • 24 = hai mươi tư (Northern preference) or hai mươi bốn (Southern/formal preference, both are standard)
  • 40 = bốn mươi (never tư mươi)
  • 44 = bốn mươi tư (or bốn mươi bốn)
  • 104 = một trăm linh bốn / linh tư (North) or một trăm lẻ bốn / lẻ tư (South)
  • 140 = một trăm tư or một trăm bốn (shorthand)
  • 1/4 = một phần tư

Examples (5)

  1. Lớp tôi có hai mươi tư học sinh.

    My class has 24 students.

    Word by Word: Class I have two ten four student.

    Here, 'tư' is used for the number 24, which is heavily favored in the North. Both 'hai mươi tư' and 'hai mươi bốn' are standard and correct, though 'bốn' is often used in the South or in formal written documents nationwide to avoid ambiguity.

  2. Hôm nay là thứ tư.

    Today is Wednesday.

    Word by Word: Day this is ordinal four.

    For Wednesday, 'thứ tư' is mandatory. You cannot use 'bốn' for days of the week.

  3. Em gái tôi mười bốn tuổi.

    My younger sister is 14 years old.

    Word by Word: Younger sister I ten four age.

    For counting and age, 'mười bốn' is the standard form for 14. While 'mười tư' exists, it is generally reserved for lunar calendar dates and traditional phrases.

  4. Cái áo này giá một trăm tư.

    This shirt costs 140.

    Word by Word: Classifier shirt this price one hundred four.

    In spoken shorthand, 'một trăm tư' means 140 (dropping the 'mươi'). Note that 'một trăm bốn' also means 140 in this context. To say 104, you must use a filler word, and can say 'một trăm linh bốn / linh tư' or 'một trăm lẻ bốn / lẻ tư'.

  5. Trường có bốn trăm học sinh.

    The school has 400 students.

    Word by Word: School have four hundred student.

    When 4 is the leading digit of any unit (like 40, 400, or 4,000), it is always 'bốn', never 'tư'.

Common Mistakes

  • Using 'mười tư' for basic counting or age instead of 'mười bốn'.

    Tôi có mười tư quyển sách.
    Tôi có mười bốn quyển sách.

    For counting items or stating age, 14 is 'mười bốn'. The form 'mười tư' is not a strict error, but it is reserved for specific contexts like lunar calendar dates (ngày mười tư).

  • Thinking that 'một trăm bốn' means 104 in everyday spoken shorthand.

    Cái này giá một trăm bốn.
    Cái này giá một trăm linh bốn.

    In spoken shorthand, dropping the trailing zero means both 'một trăm tư' and 'một trăm bốn' mean 140. To say 104, you must use a filler word: 'một trăm linh bốn / linh tư' (North) or 'một trăm lẻ bốn / lẻ tư' (South).

How It Connects

Tap a pattern to see what it builds on and what it leads to.

tưLevel 1Four in Twenty-Four and Up

Learn This First

To understand why 'bốn' (4) changes to 'tư', you first need to understand how Vietnamese constructs tens (using 'mươi') and the general concept that Sino-Vietnamese numbers are often used in specific compound structures.

Words in This Pattern

tư