When you provide a thumbnail for your plugs this thumbnail will be cropped and resized in several default sizes to fit our widgets. Because of this, it is important that your thumbnail is not too small, or it will look stretched and unclear. We recommend that you upload thumbnails with minimum:
Regular Plugs: 240x180 pixels
Gallery Plugs: 180x270 pixels
There is no maximum size. NB! Also note that plugs with unclear thumbnails, thumbnails that look stretched or has borders, graphics or watermarks, will be rejected by our admins.