Chuck,

You were correct when I added the border to make the pixel dimensions 1944x2430, Snapfish then interpretted the photo correctly as 8x10. You seem to be exactly correct in how snapfish behaves based on its "interpretation" of image dimensions. Great reverse engineering!

Thanks so much folks for all your great helpful posts. I now have the formula for resizing my pictures to do a "shrink to fit" print out, at least at Snapfish. (until they change their algorithm)

1. Calculate the pixel dimensions for the paper size,

2. change the dpi of the image so that at least 1 side of the image matches the exact pixel dimension of the paper size. (example 8 inch side)

3. Add appropriate border (white space) so the other side of the image matches the exact pixel size of the other dimension of the paper size. (example 10 inch side)

You don't need to resample your picture.

I'm restating this so that 1) you folks can correct me if I'm wrong and 2) so that the next poor sap who wants to do this, (I can't be the only one) who uses google to search for an answer, has a better chance of finding it. I found bits and pieces of the answer in my pretty extensive searching of the web but not all the steps in one place.

Thanks, again. I never would have figured this out on my own.