If you are referring to the height of a plant provided by the breeder then they state the height of the stem from soil's surface to the tip of the main stem. So if a breeder's package claims the plant will reach 1.2 meters at maturity you will want to account for the pot height as well when trying to figure out the vertical space requirements. You can measure it with the pot or without if youre in just for playing with the meter.
happy growin!