To measure for curtains, record four things: the span of the track or pole, the drop from the point where the curtain will hang to where you want the hem to finish, anything near the window that the curtain must clear, and the wall space available for the curtain to gather when it is open.

Sheer curtains let filtered daylight into the room. Blackout curtains are made to stop light from passing through the fabric. That one difference decides most of the choice. A sheer softens the light, gives some daytime screening and keeps the room bright, but it will not darken the room and gives little privacy once your