For Future Reference: The Pixel size of a photo for Instagram is currently 612×612. Anything larger will be reduced via Instagram… which is all well and good, unless you have text, then things might get a bit pixelated.
I advise resizing a photo yourself (PicMonkey is a great free online photo editor) so your Instagram pic will show up exactly like you want it to 😀
I learned this the hard way on May 4th.
Now I know!