Typically, curtain rods should be placed 5 to 6 inches above the top of the shower wall. This allows space for the curtain to hang without touching the floor.
Allow no more than 6 inches between the bottom of the shower curtain and the floor when the curtain is hung on the rod. This measurement is a standard guideline when the shower has no defining wall or shell to measure from.
Adjust the shower curtain height to best suit your shower. If the shower is a walk-in and has very little protection to keep water from spilling onto the floor, hang the curtain lower and closer to the floor to reduce over spray.