Projector aspect ratio is the width-to-height ratio of the displayed image, measured in inches. Some projectors can support multiple aspect ratios. The most common aspect ratios for projectors are 4:3, 5:4, and 16:9. That means that the chip (or panel) inside the projector is shaped in the specified 4:3, 5:4 or 16:9 proportions. The chip is like a miniature version of the image you will see on your screen.