The difference between the cost price and the retail price of merchandise. Markup may be expressed in dollars or as a percent. If stated as a percent, it may be based on either cost price or retail price. Most retailers base markup on retail price.
Measure the entire shape of a curved shower rod if this is the style you have. Expect the measured width to be approximately 6 inches more than a standard curtain rod. Purchase a shower curtain with a 72-inch width, if available, to compensate for the additional width. If necessary, a 70-inch curtain width works as well. This is because the rods curve inward at the edges, making for an overall smaller width measurement.
If you want a curtain that is easy to open and close, you could try a crane rod or curtain crane. It is a rod that is only mounted to the wall on one side and can be swiveled against the wall or opened 90 or 180 degrees. I will use one for the little window in my little toilet room off of the bathroom.