What Height Shade Do I Need For My Lamp?
There are no hard and fast rules on what shade size you choose for your lamp base, but here is a guide to get you started:
1) The shade diameter (width) should be the same as the base height (not including the bulb fittings).
2) The height of the shade should be around three quarters of the height of the base. For harp fittings, the height should be enough to totally cover the bulb fitting at the bottom when attached to the finial at the top.

Of course, rules are made to be broken and different effects can be created using shades that are taller or shorter. This floor lamp is in a tight corner in a small room, so a wide shade wouldn’t fit. The tall tube shape slots in nicely.