A rhinoplasty procedure is not a mathematical equation, it's an artform. A full set of photographs of the entire face are required to make a determination about overall projection of the nose in relation to the chin and other facial features. For many examples, please see the link below to our before and after rhinoplasty photo gallery
There are no standard nose lengths to compare. More importantly is if your nose is proportional to your face. This can be determined by clinical photography. Overall if you think your nose is to long, then probably you should have a consultation to consider surgical options. It's the overall harmony of your face and nose that matters.