Those are good standard sizes. U.S. customers can easily find ready made mats and frames for art in those sizes, making it a lot less expensive for them than custom framing. Good Luck!
Agreed. I don't know if any people buy 5 x 7".... I have only sold a few at craft shows so I took them out of my listings because I never sold any online (although I have purchased a few.... ) because I like little bits of art all over the house.
As an artist, my favorite size to paint is HUGE, but that doesn't work well with shipping, so I sell a lot of 16x20 paintings. I offer 16x20 and larger, but I know people selling prints probably opt for smaller sizes as well. :)
The sizes you listed are good sizes. Customers can buy the ready made mats to fit and then frame. I sell a lot of 5x7 and 8x10 for my original watercolor. It is good to have different price points for the sizes be it a print or an original.
