Welcome to our quick tutorial on sizing a rough opening bifold door! An essential step to ensure your door fits perfectly, let's dive in and learn how to measure the space for the door or the opening size. We'll illustrate with an example of a door with a nominal size of 36 inches by 80 inches, which has an actual size of 35 and a half by 79 inches. The opening size to fit this door should be up to 36 inches by 81 inches. For a four door bifold, the opening size can be up to 72 inches by 81 inches. Each bifold panel is actually 17 and three quarters inches wide and 79 inches in height, giving us a total width of 35 and a half inches. Considering the second bifold, for a space measuring 72 inches by 81, we'd use two bifolds, each 35 and a half by 79 inches. To sum up, bifolds are marginally smaller for an optimal fit. #DIY #Doors #BifoldDoors #HomeImprovement #HomeDIY