Please note the special issues associated with creating PHOTO STAMPS:

IMPORTANT note on ALL stamp orders!
Please note the requirements below as they relate to the images being printed on photo stamps.  Because of the nature of stamp orders, once an order is printed, there can be NO refunds or reprints due to image errors in preparation. 

Size / Resolution:

Stamps are 1.2" x 1.5" in size.  To prepare an image to that exact size based on the standard 300 dpi resolution would end up with an image that is only 360 x 450 pixels in dimension.  That is a relatively small file to work with.

Because of that, we recommend an image that is 4" x 5", which, when calculated at 300 dpi, results in an image that is 1200 x 1500 pixels in dimension.  Any image approaching that much resolution (or greater) will work sufficiently for photo stamps.  (Also, an image cropped for an 8x10 will work just as well.)

Note on Cropping: 
Image files for photo stamps MUST be cropped to that exact size to ensure that the image is properly printed.

That would mean the following:
Portrait (vertical) orientation:  4/5" = exact aspect ratio of .80
Landscape (horizontal) orientation:  5/4" = exact aspect ratio of 1.25