This results from the final image size. Let's assume that you want to have 100" on the screen. According to the information in the product, the minimum distance is 1.15:1 and the maximum distance is 1.50:1. This means that 100 "x1.15 results in a distance of 115" from the screen to the projector and a maximum of 150" to the projector. I hope I haven't made a mistake🙈