Not possible vs That's impossible

When to use each in English, with meaning, register, and examples.

Not possible

Top 2,000 (common)

That's impossible

Top 2,000 (common)
 Not possibleThat's impossible
Pronunciation🇬🇧 //nɒt ˈpɒsəbl//🇺🇸 //nɑt ˈpɑsəbl//🇬🇧 //ðæts ɪmˈpɒsəbl//🇺🇸 //ðæts ɪmˈpɑsəbl//
MeaningSomething that cannot happen or be done.It cannot be done.
ExampleIt is not possible to finish the project without more time.When I heard his plan, I thought, 'That's impossible.'
RegisterNeutralNeutral
How commonTop 2,000 (common)Top 2,000 (common)
Collocationsnot possible to achieve, not possible due to circumstances, not possible at this time, not possible without effortThat's impossible to believe, That's impossible to achieve, That's impossible to accept
Common mistakesConfusing with 'impossible' as it is less formal., Using 'not possible' when something could be possible with effort., Misplacing the phrase in a sentence leading to awkward construction.Using 'that's impossible' too casually in formal discussions., Confusing the expression with 'it's impossible' when addressing multiple situations., Overusing the phrase for minor challenges.
Usage notesUse 'not possible' in everyday contexts to indicate something is impractical or unachievable. Avoid overusing in formal writing.Use this phrase to express disbelief or skepticism in a situation. It is suitable for informal and formal situations, but can sound a bit strong depending on tone.

See it in real clips

Not possible
That's impossible

Frequently asked questions: Not possible vs That's impossible

What's the difference between Not possible and That's impossible?

Not possible: Something that cannot happen or be done. That's impossible: It cannot be done.

Can you show an example of each?

Not possible: It is not possible to finish the project without more time. That's impossible: When I heard his plan, I thought, 'That's impossible.'

Can I use Not possible and That's impossible interchangeably?

Not always. Not possible and That's impossible 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.

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