How to measure the drop:

How to measure the drop: Use of wooden or metal tape is necessary. Check: Whether the rail is even? To be sure you can take a drop measuremnet in the middle of the rail, and the at each end. Measure carefully. It is important to decide where you want the curtains to finish -popular choices include just above or just below the window sill. above a table below the window or till the floor or above the carpet. Allow a 1/2" clearance above a table or carpet. If their is no carpet then 1" to 1-1/4" clearance will help not to spoil the curtain with dust and dirt.