If your joining me from the mail club, you’ve got an A5 print so you’ll be needing an A4 frame with an A5 mount. The mount is the piece of thick white paper witH little window for your artwork. It looks better with a mount, but if you do want it to fill the whole frame you can by a frame the same size. A4 is standard printer paper size. A5 is half of A4. A3 is double A4. You get the gist.