Collocation

I'm not sure about that.

verb + (not) + adjective + preposition B1 verb + (not) + adjective + preposition

To express uncertainty or doubt about a statement, idea, or situation.

Definition

'I'm not sure about that.' is a common English collocation. To express uncertainty or doubt about a statement, idea, or situation.

be + not sure + about + [pronoun/topic]

“I'm not sure about that new policy; it seems a bit complicated to implement.”

Are you joining us for dinner tonight? I'm not sure about that; I might have to work late.
He promised to help us with the move, but I'm not sure about that. He often changes his mind.
They said the train would be on time, but I'm not sure about that. It's usually delayed.

Show more examples

You think we can finish the entire project by tomorrow? I'm not sure about that.
My boss mentioned a potential pay raise, but I'm not sure about that until I see it in writing.
He's very confident in his new business idea, but honestly, I'm not sure about that.
She wants to invest all her savings in that risky venture, but I'm not sure about that decision.
They're claiming their new product is revolutionary, but I'm not sure about that without more evidence.
You expect me to believe that elaborate story you just told? I'm not sure about that.
The government announced new regulations, but I'm not sure about that impacting us directly yet.