Step 1 : Measure width: Measure the width of the hanging rod, excluding the bracket. In case of channel, measure from one end of the channel to the other end of the channel. If you do not have a curtain rod/ channel installed, measure the width of the window and add 3 inches on each side of the window as rod buffer.
Step 2 : Measure height: Measure from the top tip of the curtain rod/ channel, to the height you desire the curtain to fall. If you do not have rod/ channel installed yet, measure the from the top of the window to the height you desire the curtain to fall and add 4 inches to it as the rod buffer.
Recommendation:
For floor touching curtains, we recommend the curtain to fall 2 inches above the floor. For window length curtains, we recommend the curtain to fall 7-8 inches below the sill of the window.