Hey Drew, This is something I caught: You stated to only measure the front of the jacket while measure both front and back of your shoulder. For the ratio, what would go up in the numerator for the jacket's measurement since you only asked for the front? Shouldn't there be a measurement of the jacket's back as well so a person can calculate the ratio for the back shoulder? Not drew, but you're right. I think he forgot it because the back shoulder is computed from the front shoulder. Just measure the back shoulder as well.