There are a couple of steps that you need to follow in order to pick the most suitable size for your window shape and size. Firstly be sure that you grab a measuring tape and a blank piece of paper. Moving on, begin measuring the width of the rod from left to right and the distance from the curtain's top to the floor (total length of the curtain). Next, write down the dimensions of your piece of paper and start looking for the most fitting size. A general rule that you should remember is that the width of the curtain should be at least 2 times the width of your rod. Lastly, if you're still encountering issues, then reach out to the company for extra assistance.