That's impossible vs Unlikely

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

That's impossible

Top 2,000 (common)

Unlikely

Top 2,000 (common) B1 adjective

	That's impossible	Unlikely
Pronunciation	🇬🇧 //ðæts ɪmˈpɒsəbl// 🇺🇸 //ðæts ɪmˈpɑsəbl//	🇬🇧 /["/ʌnˈlaɪkli/"]/ 🇺🇸 /["/ʌnˈlaɪkli/"]/
Meaning	It cannot be done.	Not likely to happen or to be true.
Example	When I heard his plan, I thought, 'That's impossible.'	It is unlikely that it will rain today given the clear skies.
Register	Neutral	Neutral
How common	Top 2,000 (common)	Top 2,000 (common)
CEFR level	-	B1
Part of speech		adjective
Collocations	That's impossible to believe, That's impossible to achieve, That's impossible to accept	appear, be, look, extremely, fairly, very, appear, be, look, extremely, fairly, very, appear, be, look, extremely, fairly, very
Antonyms	-	likely, probable, certain
Common mistakes	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.	Confused with 'unlikely' vs 'unlikelyhood', Incorrectly using it in an informal context where 'improbable' might fit better., Using 'unlikely' to describe a person's character instead of a situation.
Usage notes	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.	Use 'unlikely' to describe situations or outcomes that are not expected. It's more appropriate in neutral contexts; avoid in very formal writing.

See it in real clips

That's impossible.

That's impossible

Succession › S1 E1

in the event of my unlikely demise,

Sherlock › S1 E1

Unlikely you've got an extended family, not one you're close to.

Succession › S1 E1

in the event of my unlikely demise,

Sherlock › S1 E1

Unlikely you've got an extended family, not one you're close to.

Unlikely

Frequently asked questions: That's impossible vs Unlikely

What's the difference between That's impossible and Unlikely?

That's impossible: It cannot be done. Unlikely: Not likely to happen or to be true.

Can you show an example of each?

That's impossible: When I heard his plan, I thought, 'That's impossible.' Unlikely: It is unlikely that it will rain today given the clear skies.

Can I use That's impossible and Unlikely interchangeably?

Not always. That's impossible and Unlikely 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.