Cool MateNot a clue vs Not sure
When to use each in English, with meaning, register, and examples.
Not a clue
InformalTop 2,000 (common)
Not sure
| Not a clue | Not sure | |
|---|---|---|
| Pronunciation | 🇬🇧 //nɒt ə kluː//🇺🇸 //nɑt ə klu// | |
| Meaning | I don't know anything about it. | |
| Example | I have not a clue where my keys are. | - |
| Register | Informal | - |
| How common | Top 2,000 (common) | - |
| Collocations | not a clue about, not a clue how, not a clue where | - |
| Antonyms | completely sure, certain, fully informed, aware | - |
| Common mistakes | Confused with 'have a clue' (meaning to know something)., Incorrectly using in formal contexts., Misplacing 'not' (e.g., saying 'have not a clue'). | - |
| Usage notes | Used in casual conversation to express ignorance about a topic. Not suitable for formal writing. | - |
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Frequently asked questions: Not a clue vs Not sure
What's the difference between Not a clue and Not sure?
Not a clue: I don't know anything about it. Not sure:
Can I use Not a clue and Not sure interchangeably?
Not always. Not a clue and Not sure are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.