Meaning
Realizing one has forgotten something.
Cultural Background
The phrase is often accompanied by a physical gesture: a light slap to the forehead or the cheek, symbolizing the 're-awakening' of the memory. Young people often use 'Não cá vàng' (Goldfish brain) alongside 'quên mất' to joke about their poor memory in a high-stress, digital world. In Vietnamese business, 'quên mất' is a common 'soft' excuse. It is often more acceptable to say you forgot than to say you didn't understand or didn't care. In the South, 'quên mất tiêu' is extremely common. 'Tiêu' adds a sense of something being 'consumed' or 'gone forever,' making the forgetting sound more dramatic and casual.
Add 'rồi' for naturalness
Always add 'rồi' at the end of 'Quên mất' when speaking. It makes you sound 10x more like a native speaker.
Don't over-apologize
For small things like forgetting a pen, 'Quên mất' is enough. You don't always need a heavy 'Xin lỗi'.
Meaning
Realizing one has forgotten something.
Add 'rồi' for naturalness
Always add 'rồi' at the end of 'Quên mất' when speaking. It makes you sound 10x more like a native speaker.
Don't over-apologize
For small things like forgetting a pen, 'Quên mất' is enough. You don't always need a heavy 'Xin lỗi'.
The 'Goldfish' joke
If you forget something twice, say 'Mình là não cá vàng' (I'm a goldfish brain). It always gets a laugh.
Test Yourself
Fill in the blank with the correct phrase to say 'I forgot my phone.'
Tôi ___ điện thoại rồi.
'Quên mất' is the standard way to say you forgot an object.
Which sentence means 'I forgot to buy water'?
Select the correct sentence:
In Vietnamese, 'quên mất không' + [verb] is the correct pattern for forgetting to do something.
Match the response to the situation.
Situation: Your friend asks why you didn't call them yesterday.
This is the most natural and polite way to apologize for forgetting a task.
Complete the dialogue.
A: Bạn có mang sách không? B: Ôi, mình ___ ở nhà rồi!
'Quên mất' fits perfectly here to indicate leaving something behind by accident.
🎉 Score: /4
Visual Learning Aids
Practice Bank
4 exercisesTôi ___ điện thoại rồi.
'Quên mất' is the standard way to say you forgot an object.
Select the correct sentence:
In Vietnamese, 'quên mất không' + [verb] is the correct pattern for forgetting to do something.
Situation: Your friend asks why you didn't call them yesterday.
This is the most natural and polite way to apologize for forgetting a task.
A: Bạn có mang sách không? B: Ôi, mình ___ ở nhà rồi!
'Quên mất' fits perfectly here to indicate leaving something behind by accident.
🎉 Score: /4
Frequently Asked Questions
10 questionsYes, but 'Quên mất' sounds more natural when you've just realized your mistake.
Yes, it's neutral. To make it very polite, add 'Dạ' at the beginning and 'ạ' at the end.
'Quên béng' is much stronger, like 'totally forgot' or 'it completely slipped my mind.'
You can use it for forgetting a person's *name*, but saying you forgot the person themselves sounds like you forgot they existed!
In this context, it's a particle indicating an accidental result, not a literal loss of a physical object.
Use the pattern: Quên mất + không + [Verb]. Example: 'Quên mất không ăn' (Forgot to eat).
Yes, it's universal, though the South might add 'tiêu' after it.
It's better to use 'Tôi sơ suất quên...' or 'Tôi chưa kịp...' in very formal emails.
It is the 'sắc' tone (high rising).
Because you are forgetting the act of *not* doing something, or rather, the result is that the action did *not* happen.
Related Phrases
Quên béng mất
specialized formTo completely and suddenly forget.
Quên rồi
similarForgot already.
Nhớ ra
contrastTo suddenly remember.
Lãng quên
synonymTo fade into oblivion.
Sơ suất
specialized formAn oversight or negligence.
