All print sizes are the sizes to fit a frame - *important* - NOT the printed image size. The prints include a BORDER by way of a mount or including the border on the print edge, and as such the Print Size you select is the overall paper size that you would fit into a frame.
Hence when you select a 8"x12" Sized print, you will actually get a 6"x10" print of the image on 8"x12" paper. This will allow your image to fit into a 8"x12" frame with a 1-inch border at each end.
If you would rather have a print without a border and have the full dimensions let me know and I can do that for you as well.
Frame BORDER / MOUNT Sizing as follows:
For STANDARD and OAK FRAMES
5"x7" print with 4"x6" image
8"x12" with mount and 6"x10" image
12"x16" with mount and 10"x14" image
16"x20" with mount and 14"18" image
20"x30" print with 16"x26" image
24"x36" print with 20"x32" image
A4 = 8.27" x 11.69" with mount and 6.27" x 9.69" image
A3 = 11.69" x 16.53" with mount and 9.69" x14.53" image
A2 = 16.53" x 23.39" with mount and 14.53" x 21.39" image
A1 = 23.39" x 33.11" Print with 19.39" x 29.11" image
For the FINEART FRAME
A4 = 8.27" x 11.69" with mount and 5.83" x 9.50" image
A3 = 11.69" x 16.53" with mount and 8.07" x13.16" image
A2 = 16.53" x 23.39" with mount and 11.54" x 18.39" image
A1 = 23.39" x 33.11" Print with 16.39" x 26.11" image
Border example

I can do different border sizes on request, just drop me an email beforehand
NOTE if buying just a print without a frame and a border has been selected, I will include the border as part of the image, so you can simply place the image in your own frame.