Hanging curtain rods and measuring for drapes can be complicated. I’m sharing my method for getting the rod and drape hung perfectly!
Drapery websites like Two Pages (where I’ve bought all my drapes from) have a measuring tool you can use. I just hung several rods and drapes around my home and here’s what worked:
For custom drapes where you can select the width and length, I hang the curtain rod first. Typically, I hang the rod 1 foot above the window trim, and extend at least 6 inches out past the sides of the window trim. In the graphic below, this door was already 10′ tall and I didn’t feel the need to extend a full foot above. I went 6″ above and 6″ out from each side. Also, on my bedroom windows, I hung at the midway point between the ceiling and the window trim. You can decide which height seems best for you- but with shorter ceilings, it’s always best to hang higher to make the ceilings feel taller.

Your curtain rods will come with hanging hardware. Don’t use the thin anchors that they provide- use these! They will support the rod more and not come loose in the drywall. And of course, if you’re able to hit studs instead, that is best.
Once your rod is hung, measure from the floor to the BOTTOM of the rod. Subtract 1″. This will be the total LENGTH of your drapes. I measure on each end of the rod to make sure I’m getting the same measurement at each end.
Your pleated drapes will come with adjustable hooks so you can lengthen or shorten your drapes a little. You will need curtain rings like these here to attach the hooks to the rod.
For the WIDTH of your drapes, take the total width of your rod and divide by 2.
I used this method to hang all the drapes in my home, and my drapes hit the floor perfectly!