Everyone s face is different, so there is not a perfect ratio that would suit everyone. Historically, the ideal ratio of the vertical height of the upper lip to that of the lower lip is 1: 1.6. This means that the lower lip is 1.6 times the height of the upper lip and the width of the mouth should be 1.6 times the width of the bottom of the nose. There are so many factors that influence a lip ratio including the amount of white lip visible, the shape of your face, your bone definition and even the length of your teeth. For most people, the ideal lip length will be anywhere from 9mm 8mm but it all will depend on the overall features of the entire face.