In order to know what size your image will be suitable for print you will first need to know the resolution of the image in pixels (for example 1024 x 768 pixels).
As our recommended pixels-per-inch (PPI) is 300, divide these dimensions by 300 to find out the maximum recommended size (in inches) for that image.
Hence, a 1024 x 768 pixel image should not be larger than 3.4 x 2.56 inches in the design, as calculated below:
Width: 1024 ÷ 300 = 3.4 inches
Height: 768 ÷ 300 = 2.54 inches
See: Image quality