Way 1 · best default
I'm afraid I don't know
Polite and honest. "I'm afraid" adds a little "sorry" so it doesn't sound cold.
Examples
I'm afraid I don't know, I'm not from round here.
Sorry, I'm afraid I don't know what time it closes.
In a conversation
A: Excuse me, is there a pharmacy near here?
B: I'm afraid I don't know, sorry. I'm just visiting.
Common mistake
Not: I don't know about it.
Say: I'm afraid I don't know.
"About it" is extra here. Just "I don't know", softened with "I'm afraid".
