ICO is the Windows icon format used for application icons and website favicons, able to hold several small sizes in one file.
Part of Windows since its earliest versions, ICO bundles multiple resolutions (16×16, 32×32, 48×48 and more) so the system picks the sharpest.
Use ICO for favicons and desktop icons; to edit the artwork, convert it to PNG and back.
Advantages
- ✓Supports transparency (an alpha channel).
Drawbacks
- ✕Limited support outside specific apps or platforms.
- ✕Inefficient for full-color photographs.
Frequently Asked Questions
Is ICO lossy or lossless?
ICO is lossless, so it preserves image quality exactly without throwing any data away.
Does ICO support transparency?
Yes, ICO supports transparency, so transparent backgrounds are preserved.
How do I open or convert a ICO file?
Most image viewers can open ICO files, but for full compatibility you can convert ICO to JPG or PNG right here — free, instant and private in your browser.