Mandarin Negation: 不 vs 没
English gets by with one "not". Mandarin has two, 不 (bù) and 没 (méi), and they split the work cleanly: 不 negates what is true now, what will be true, what is habitually true, and adjectives; 没 negates completed past actions. They are not interchangeable, the choice between them is one of the first grammar decisions you make in every negative sentence, and the good news is that the rule is small enough to fit on an index card. This page is the whole rule.
The two negators at a glance
| Negator | Pinyin | Negates | Example | Translation |
|---|---|---|---|---|
| 不 | bù | Present, future, habits, willingness, adjectives | 我不去 (wǒ bú qù) | I am not going |
| 没 | méi | Completed past actions, and 有 | 我没去 (wǒ méi qù) | I did not go |
The same verb, 去 (qù, to go), with the two negators, gives two different meanings. 我不去 is a statement about now or the future: I am not going, I refuse to go, I do not go. 我没去 is a statement about the past: the going did not happen. That minimal pair is the entire system in miniature.
不 (bù): the present, the future, habits, and adjectives
不 goes directly in front of the verb (or adjective), and nothing else in the sentence moves. If the English negative is "don't", "won't", "isn't" or "not + adjective", you want 不.
| Sentence | Pinyin | Translation |
|---|---|---|
| 我不去 | wǒ bú qù | I am not going / I will not go |
| 我不知道 | wǒ bù zhī dào | I do not know |
| 他不是我先生 | tā bú shì wǒ xiān shēng | He is not my husband |
| 我不喜欢这个 | wǒ bù xǐ huan zhè ge | I do not like this one |
| 我不想去 | wǒ bù xiǎng qù | I do not want to go |
| 这个不好 | zhè ge bù hǎo | This one is not good |
Three of those deserve a note:
- 不是 (bú shì): the copula 是 always negates with 不, never 没. Chapter 3 covers 是 in full; for now, 不是 is the fixed shape of "is not".
- 不想 / 不要 (bù xiǎng / bú yào): willingness and wanting are states, not completed events, so they take 不 even when you are talking about a past refusal.
- 这个不好 (zhè ge bù hǎo): adjectives take 不 directly. There is no "is" in the Mandarin sentence to negate; the adjective carries the meaning "to be good" on its own, and 不 flips it.
没 (méi): the past that did not happen
没 negates actions that were expected, possible or supposed to happen, and did not. If the English negative is "didn't" or "hasn't", you want 没.
| Sentence | Pinyin | Translation |
|---|---|---|
| 他没来 | tā méi lái | He did not come |
| 我没去 | wǒ méi qù | I did not go |
| 她没说什么 | tā méi shuō shén me | She did not say anything |
| 我没看到 | wǒ méi kàn dào | I did not see it |
| 他没告诉我 | tā méi gào sù wǒ | He did not tell me |
Notice what is missing from every one of those sentences: any past-tense marking on the verb. 没 does the "did not" work by itself. The verb stays in its bare dictionary form, exactly as it appears on its word page. This matters because of beginner error number three below.
有 (yǒu) only ever takes 没
有 (yǒu, to have / there is) is the one verb in the language with a fixed negator: 没. The negative of 有 is 没有 (méi yǒu), in every tense, in every context, with no exceptions.
| Sentence | Pinyin | Translation |
|---|---|---|
| 我没有事 | wǒ méi yǒu shì | I have nothing on |
| 我没有这个 | wǒ méi yǒu zhè ge | I do not have this |
| 这里没有人 | zhè lǐ méi yǒu rén | There is nobody here |
不有 does not exist. It is not rare, not formal, not regional: it is simply not Mandarin. Because English speakers default to 不 as "the" negator, 不有 is the single most common negation error in a beginner's first month. When 有 shows up, the 不-vs-没 decision is already made for you.
In speech, 没有 frequently shortens to bare 没 before a noun: 我没事 (wǒ méi shì, I am fine / nothing is wrong). Both forms are correct; 没有 is the full shape to learn first. Chapter 3 covers 有 and possession in full.
The tone change: bù becomes bú before a fourth tone
不 is a fourth-tone syllable, bù. But Mandarin does not like two fourth tones back to back, so when the syllable after 不 is also fourth tone, 不 shifts to second tone: bú. The character never changes; only the pronunciation does. This is tone sandhi, and it is automatic and obligatory, not optional colouring.
| Written | Pronounced | Why |
|---|---|---|
| 不是 | bú shì | 是 is fourth tone, so 不 shifts |
| 不去 | bú qù | 去 is fourth tone, so 不 shifts |
| 不要 | bú yào | 要 is fourth tone, so 不 shifts |
| 不会 | bú huì | 会 is fourth tone, so 不 shifts |
| 不好 | bù hǎo | 好 is third tone, no shift |
| 不来 | bù lái | 来 is second tone, no shift |
| 不说 | bù shuō | 说 is first tone, no shift |
| 不能 | bù néng | 能 is second tone, no shift |
没 (méi) has no sandhi of its own; it is second tone everywhere. See the pinyin and tones page for the other big sandhi rule (third tone + third tone).
The four beginner errors
- 不有. Does not exist. The negative of 有 is 没有, always. If you catch yourself about to say 不有, say 没有 and move on.
- 没 for the future or for habits. 没 is for things that did not happen. "I am not going tomorrow" is 我明天不去 (wǒ míng tiān bú qù), never 我明天没去. If the event has not had its chance to happen yet, 没 cannot negate it.
- 没 + 了 together. The completion marker 了 (le) and 没 do the same job from opposite directions, so they do not stack. "I did not go" is 我没去, not 我没去了. When 没 arrives, 了 leaves.
- 没 with adjectives. "This is not good" is 这个不好, not 这个没好. Adjectives are states, and states belong to 不.
The cheatsheet
| Situation | Negator | Example |
|---|---|---|
| Now / future / refusal | 不 | 我不去 (wǒ bú qù) |
| Habit / standing preference | 不 | 我不喜欢这个 (wǒ bù xǐ huan zhè ge) |
| Adjective | 不 | 这个不好 (zhè ge bù hǎo) |
| Identity with 是 | 不 | 他不是我先生 (tā bú shì wǒ xiān shēng) |
| Completed past action | 没 | 他没来 (tā méi lái) |
| Possession / existence with 有 | 没 | 我没有事 (wǒ méi yǒu shì) |
| 不 before a fourth tone | bú | 不是 (bú shì), 不去 (bú qù) |
Cross-links
- Mandarin pillar for where negation sits in the first weeks of the curriculum.
- Mandarin grammar for the wider grammar map.
- The copula 是 for the full story on 是 and 不是.
- Possession with 有 for 有, 没有 and the existence pattern.
- Aspect markers for 了 and why it disappears after 没.
- Pinyin and tones for tone sandhi beyond the 不 rule.