How to Convert Icons into Different File Formats and Size
If the icon size you are looking for is not available to download, you can convert it to that specific size and format. The supported size range is from 10px - 512px or the maximum size available. The supported formats are .BMP .GIF .JPG .PNG and .TIFF
For this feature, you can use the "Convert Icon" link (as shown in picture) from the icon detail page.