How many inches high should the Menorah be from the floor?
The flames of the Menorah must be situated at least three Tefachim (approximately 10 inches) from the floor. The Menorah should not be positioned higher than ten Tefachim (approximately 31 inches).
Many Poskim say that it is sufficient if part of the body of the Menorah is below ten Tefachim, even if the flames are above ten Tefachim. It is not the Chabad custom to specifically position them between seven and ten Tefachim, or close to three. In the event that one did light the menorah above ten Tefachim, he has fulfilled his obligation. However, if one lit twenty Amos (approximately 30 feet) or higher, it must be relit.
See halacha2go.com article #467: Height of Menorah for more on this subject.