ICO maximum size

Question

Is there a way to convert an image to ICO format, if the resolution is bigger than 256x256?

I found several programs but none of them was able to convert larger images. The size which I need is 1024x1024.

Answer 1

Since the width and height is stored as a single byte each in the ICO image format, it cannot represent images larger than 256×256.

You need to first resize your image.

http://en.wikipedia.org/wiki/ICO_(file_format)#Outline

Answer 2

if you comfortable with actual photo editing software GIMP is a awesome option for this it can take any single image and turn it into a multi-layer icon plus you got all the professional image editing tools at your disposal to customize the images any way you want. and it's %100 free. I use nine image layers on my icons... sizes- 256 128 64 48 40 32 24 20 and 16. to come up with this size formula I just opened a good looking icons .ico file already in use in Windows 11 and this is what I found. oh yeah and don't use compression.