Use the thumbnail resizing from imgur, appending the letter here to the jpg name:
t Small Thumbnail 160x160
m Medium Thumbnail 320x320
l Large Thumbnail 640x640
h Huge Thumbnail 1024x1024
This keeps your image proportions, so if you want it smaller:
https://i.sstatic.net/pWRSSl.jpg
https://i.sstatic.net/pWRSSm.jpg
https://i.sstatic.net/pWRSSt.jpg
