How can I determine the proper drapes size for my windows?
If you specially measure your window and send a drapes store make drapes for you, then you do not worry about the drapes sizes. If you are trying to buy ready-made curtains/drapes for your room, then you will need to measure your window and pick the proper drape sizes.
First is your windows height. You measure your windows from top to bottom. Your curtains must be at least longer than your windows height. There are many curtain lengths in the market. Mostly they are 36 in, 48 inch, 62 inch, 84 inch and 98 inch.
Second, how wide are your windows. It is common to keep 3/2 rules when determining the width of drapes. For example, your window has width of 40 inch, and then you will need drapes with 40x3 inch then divided by 2. The answer is 60 inch. In another words, 60 inch wide curtain or drapes will properly cover 40 inch around windows. Of course, it will be good for a 30 inch wide window and roughly good for a 40-45 inch wide window.