The length of the curtain you choose depends on how high you will hang the curtain rod and how close to the floor you prefer to place the curtains. A good rule of thumb is 4 to 6 inches above the window frame, but to make the room appear taller, hang them closer to the ceiling, up to 12 inches above the window frame. Choose a length half an inch above the floor for a clean everyday look. For a more luxurious puddle effect, choose curtains 6 to 8 inches longer than the stem length to the floor.