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Using 说不定 (shuōbudìng) to Express Possibility and Uncertainty in Chinese
The fixed phrase 说不定 (shuōbudìng) literally means 'cannot say for certain' and commonly functions like an adverb meaning 'maybe' or 'perhaps' to introduce a speculative outcome.
天这么阴，说不定一会儿要下雨。
Here 说不定 sits at the start of the second clause to introduce a natural guess based on what the speaker sees.
× 他今天很说不定会迟到。
Incorrect: When 说不定 means 'maybe' before a verb phrase, it functions as a fixed adverbial expression and cannot be modified by the degree adverb 很 (hěn). Replace it with the corrected sentence or use 很可能 (hěn kěnéng) if you need to express 'very likely.'
Corrected example: 他今天很可能会迟到。
Read the full explanation and examples
Core Meaning and Syllabus Scope
In the supplied HSK 4 outline, 说不定 is listed as a fixed phrase. Its literal idea is “cannot say for sure”. As a predicate it can describe something undecided; before a clause it commonly means “maybe” or “perhaps”. This page uses the common neutral-tone spelling shuōbudìng.
Rather than stating a cold mathematical probability, 说不定 usually introduces a lively guess, an unexpected turn of events, or a possibility that the listener might not have considered yet. Note that while this item sits at Level 4 in the 2025-11 syllabus outline, test takers should always check which specific syllabus version applies to their registered examination.
Sentence Positions and Structures
When 说不定 means 'maybe' or 'perhaps,' it modifies a statement about an uncertain situation. Just like other modal adverbs in Mandarin, it has two main positions in a clause.
天这么阴，说不定一会儿要下雨。
Here 说不定 sits at the start of the second clause to introduce a natural guess based on what the speaker sees.
这件事他已经知道了，他今天说不定不来了。
Here 说不定 is placed after the subject 他 (tā) and time word 今天 (jīntiān), right before the negative predicate.
Because 说不定 originated as a verb-complement phrase, it can also stand at the end of a clause as the main predicate, or be used alone as a short reply. In this position, it keeps its literal meaning of 'hard to say' or 'uncertain,' and it is often preceded by adverbs like 还 (hái, still) or 也 (yě, also).
结果怎么样，现在还说不定。
Used as the main predicate after 还 (hái), 说不定 carries its literal meaning: 'cannot be determined yet.'
Natural Contexts and Contrast with 可能
Learners frequently ask how 说不定 differs from 可能 (kěnéng, possible / maybe) and 也许 (yěxǔ, perhaps). While all three translate as 'maybe' in many sentences, they differ in register, grammar, and speaker attitude.
- Conversational tone: 说不定 belongs primarily to spoken or informal written Chinese, whereas 可能 works across both casual conversation and formal reports.
- Hinting at the unexpected: Speakers often choose 说不定 to encourage someone or point out a surprising possibility against current expectations.
- Grammatical flexibility: 可能 can function as a noun (一种可能, a possibility) or an adjective modified by 很 (很可能, very likely). When 说不定 means 'maybe,' it cannot be used as a noun.
你再去问问经理，说不定他会同意你的计划。
This shows the typical encouraging use of 说不定: suggesting a positive, slightly unexpected possibility.
Limits and Common Learner Mistakes
A common error occurs when learners treat adverbial 说不定 as an adjective or modal verb that can be graded by degree adverbs such as 很 (hěn, very) or 非常 (fēicháng, extremely), copying the English pattern 'very likely' or the Chinese phrase 很可能 (hěn kěnéng).
× 他今天很说不定会迟到。
Incorrect: When 说不定 means 'maybe' before a verb phrase, it functions as a fixed adverbial expression and cannot be modified by the degree adverb 很 (hěn). Replace it with the corrected sentence or use 很可能 (hěn kěnéng) if you need to express 'very likely.'
Corrected example: 他今天很可能会迟到。
他今天很可能会迟到。
Use 很可能 to keep the intended meaning “very likely”. 他今天说不定会迟到 is also grammatical, but it means “Maybe he will be late” and expresses a less committed guess.
Frequently asked questions
Can I use 说不定 by itself to answer a question?
Yes. If someone asks whether an uncertain event will happen, you can reply 说不定 (shuōbudìng) or 这也说不定 (zhè yě shuōbudìng) to mean 'It is hard to say' or 'Maybe, who knows?'
How is the 不 in 说不定 pronounced?
This lesson uses shuōbudìng, with neutral-tone bu. Reference dictionaries also record shuō bù dìng, with spoken shuō bú dìng when 不 takes its full tone before fourth-tone 定. These are pronunciation conventions, not different meanings. 定 is dìng, fourth tone.
