Not that big a deal?

bbserI thought "... not that a big deal" sounded more normal. Am I missing something?

Apparently you are. Your version is ungrammatical and not normal at all. The position of "a" is sometimes not where you expect it, based on other words nearby, like "that" or "so" or "such"

not that big a deal
not so big a deal

not such a big deal

Thanks, CJ.

I see. But how about this one?
It is not a deal that big.
May I say this is grammartically right but may sounds unnormal to native english speaker?

Bbser

bbserMay Can I say this is grammartically grammatically right but may sounds unnormal abnormal to native english English speaker?

Sorry. It's not even grammatically right -- at least not to my ear. Others may find it just within the bounds of correctness. To be correct with that word order you'd have to

Thanks a lot, CJ.