Imagicon is a tool for Windows which can help you convert multiple image formats at once. Like from .bmp and .png etc. to any other format that you wish, all at once without having them done singly, saving time for you. There are many similar tools, but this one is a light version and works pretty well.

This tool is a very simple and effective one, where you have to drag the images, and select the destination format for all of them and then convert them. Options are available to transform images and enable alpha transparency of icons. The interface window of Imagicon can be personalized with custom designs.
The user can select to save icons with the following dimensions in pixels: 16 x 16, 32 x 32, 48 x 48, 64 x 64 and 128 x 128. Imagicon also features the ability to drag ‘n’ drop multiple images for faster processing.

This tool is of 2MB and comes for free and full version. It works fine in Windows XP, Vista and Windows 7, NT and Win 2000. There are not much options to check in it, so its easy to use. You can download Imagicon software from here.