Step-by-step guide for using our calculator: Measure the following dimensions of each wall: width and length. We recommend entering the dimensions of each wall and calculating the required number of panels. You can enter imperial units—inches or feet—or metric system units—centimeters. Find out how many panels you need and how much it will cost. Open any product and select the recommended size and quantity. Click or tap the “add to cart” button to view the order total and proceed to checkout.