Scaling images to fit into Instagram's 4x5 ratio

[lorie229]

I would like to know how to resize my photos of my artwork so that their true shape (some are tall and narrow or long and narrow landscapes) fit into the Instagram 4x5 image ratio (I think that's what you call it) I would not mind if there would be white borders on the sides of my images. Without re-scaling my images, Instagram crops or reshapes them. Thank you for any info you can offer me.