Recommended image size for the Craigslist posts

How To Enhance and Resize Photos for Craigslist recommends monitor-reasonable image size of 800x600 and file no larger 500K.

Actually Craigslist displays just a slightly over sized thumbnail of the uploaded image with the highest dimension not larger than 300 pixels and size about 5K. However <img> and <a> HTML tags can be used to embed links to a bigger image.