How Do Rhinoplasty Surgeons Know What Will Fit?

Every patient and every rhinoplasty is unique -- there is not a "one size fits all" nose. For the nose to look natural it must adhere to some basic proportions, but it must also be in balance an harmony with the patient's other facial features.
Most rhinoplasty surgeons now use computer imaging to review and analyze the patient's own photos. The patient's photos can be morphed to simulate the surgical changes. Recently, 3D rhinoplasty imaging has become available. This allows the surgeon and the patient to view the nose from any angle and make simulated changes in 3D (see link below).

Rhinoplasty is an art. Knowing what will fit your face comes from experience, surgical skills, training, and knowledge. There are many different angles and measurements, but surgeons rarely perform these calculations. A surgeon's before and after portfolio can give you an idea of what he is capable of, especially if he has before and after photos of a patient with similar nasal anatomy to you.

Rhinoplasty, along with other cosmetic procedure are considered a real art. So when I look at a patients nose there are landmarks and specific relationships that I look at to see what is IDEAL. Now having said that, it is needs to be assessed what is the patient trying to achieve.
A combination of what you want and what is ideal for this particular face will lead you to nice result. Make sure that your plastic surgeon is board certified by american board of plastic surgery.
Good luck.