When deciding on how much to remove, I usually manually lift the lip with the patient holding the mirror and we decide together. An exam is important because there are many other factors to take into account such as skin thickness, muscle function, skin laxity, amount of tooth show present with the lips parted at rest, etc. For example, patients with thinner upper lips get more of a lift than those with thick upper lips. So even if you have the same philtral length as another person, it doesn't mean you would get the same amount of excision. With that being said, most excisions range between 5-7mm (not cm). I have a lot of videos and before/afters on Realself and Instagram. I've attached one video here.