Choose the Right Height of Lamps next to Sofas
Knowing the right lamp dimensions, too short or too tall, before you go shopping will save you time and money.
Floor Lamp If you use a combination of floor and table lamps, the top edges of all the fixtures should be within a few inches of one another. The top of a floor lamp used with a sofa should be between 58 and 64 inches tall, with the bottom of the shade being at or above the eye level of a seated person.
Table Lamp Side tables typically are 25 to 30 inches tall, and the seat of a sofa usually is about 19 inches from the floor. For a table lamp used for reading, the bottom of the lampshade should be at eye level to someone seated on the sofa. Measured from the floor, the top of the lamp should be within 58 to 64 inches. You can adjust the height of a short lamp by creating a base of stacked books or a decorative box.
source - homeguides.sfgate.com