How long it will be or How long will it be?
How do I write it correctly (see above)?

Question

Answer

How long will it be.

Answer

Thank you Zowee! Good answer.
It was a quastion.  And now I know that "How long will it be?" is right variant.

Answer

If it's a question, then 'How long will it be' [before you graduate?]
If it's in a sentence then you could say 'I don't know how long it will be before I graduate'.....so it depends on the context, but as Andrew says, it is most likely you are asking a question and therefore it would be 'How long will it be...?'

You might want to write a complete question as it also could be 'How long is it?' etc

thanks! :)