While you calculate the distance do you start from the bottom or the top?

You start at the bottom

Distance, often assigned the variable d, is a measure of the space contained by a straight line between two points. Distance can refer to the space between two stationary points (for instance, a person's height is the distance from the bottom of his or her feet to the top of his or her head) or can refer to the space between the current position of a moving object and its starting location.