Is this sentence ok without "or not"?

Whether we go out will depend on the weather
=> Is the above sentence all right without “or not”? By the way, if we use “upon” instead of “on” in that sentence, will it sound more formal?

Thanks a lot

I’d say ‘or not’ is optional. However, I’d also say that isn’t exactly the most elegant sentence ever written. :wink:

Yes, saying ‘depend upon’ generally sounds more formal than ‘depend on’.