Making sure the curtain rail is level depends on the kind of drapes you’re installing. There many different types of curtain tracks and poles and they will all have their own installation procedures. Most of these methods are very similar and easy to complete.
Measuring - The track needs to be between 4 to 6 inches above the window recess although you can position it lower if there isn’t much space available. Ideally, the curtain track should be midway between the window and the ceiling. Occasionally, you might have to alter this general rule so the curtain track is in direct proportion for the space you are working in. There might be times you’ll need to alter the position of the brackets holding the curtain rail when there are obstructions you can’t move.Mark a line at the correct level. When this is done, make measurements for the curtain track brackets. These should be 6 inches on either side of the window on the line you’ve already marked. To be certain your line is level, put a nail in each of the bracket markings and run a string line between them to ensure they’re level (with a smaller window you can use a spirit level). Make any adjustments if necessary.Some curtain tracks will require a center bracket, especially on wider windows. To fix them into position, measure from the mark on one side bracket to the other and make a mark in the center. Where there are several brackets, measure up so they are equally spaced.