WIDTH: Use a steel tape measure and measure your window from end to end. Then install your track/rod to #t window width. Once track/rod has been installed you can then work out the drop you need to cover window
For curtain tracks measure from the top of the curtain track down to the level you want curtains to hang.
A slight variance in drop can be achieved by the size of the type of hook you use or if hanging pencil pleat curtain using the di#ernt hook pocket levels.
For more information on blinds, shutters and curtains, visit our friends at NCR Blinds