Hi, Anne! Welcome aboard! I make my thumbnails and convert .bmp to .jpeg with Paintshop Pro. It lets you re-size any image in any format. I use it also to re-size huge rendered bitmaps to a size I can view as desktop wallpaper. Another option may be to just re-size your image with Ultrafractal to the size thumbnail you need (typically 200x150 or 200x200 for square ones) and export that as a thumbnail. Rick