What is a ICO file?
ICO — Windows icon
Use the format ICO
A concrete example
Extract a PNG visual from an icon to reuse it in a presentation.
Useful checks
An ICO can combine multiple sizes. Check that the chosen resolution is suitable for the intended use.
Choose a conversion
Keep the original and open the result in the software or on the device that will need to use it.
Your questions about this format
How to convert a HEIC photo from iPhone for free?
Choose your HEIC file in Images, then JPEG to share it widely or PNG if your usage requires it. Proceed to preparation, check the output, and start the conversion. Download and open the result. HEIC remains free; size limits and daily quota apply.
JPEG, PNG or WEBP: how to choose?
For a photo to send, start with JPEG. For a logo with transparency or sharp text, prefer PNG. For a web publication, WEBP can be interesting: compare the size and the rendering before publication. Converting a JPEG to PNG does not restore details lost earlier.
Why does my transparent background become opaque?
JPEG does not preserve transparency. Choose PNG or WEBP when the background must remain transparent and the proposed conversion allows it. If the background is already flattened in the original file, changing the format will not remove it.
Will my Photoshop layers or my vector drawing be preserved?
A JPEG or PNG output is a flattened image. It does not retain PSD layers or the editable objects of an SVG or an Illustrator file. Keep your working file and use the exported copy for sharing. Specialized creation formats are indicated by NoLimit.
What is it?
ICO is the Windows icon format. Its distinctive feature is that it bundles several versions of the same image inside a single file: 16, 32, 48, 256 pixels square, in various colour depths.
The system then automatically picks the size that fits the context — a thumbnail in a list, a large icon on the desktop — without ever having to resize anything.
History & origin
The format dates back to the earliest versions of Windows in the 1980s and evolved alongside them: transparency was added, then internal PNG compression for the larger sizes.
The web gave it a second life through the favicon, that small icon shown in the browser tab, long served under the name favicon.ico.
Why it is useful
Multiple resolutions in a single file: exactly what an icon needs, since it must stay legible at both 16 pixels and 256.
It remains universally recognised by browsers, including older ones.
Limits & drawbacks
It's a single-purpose format: it's only good for icons, nothing else.
It's poorly suited to very high-density screens, where SVG and large PNGs have now taken over.
Practical tips
For a favicon, start from a decent-sized square PNG and convert it to ICO: the multiple sizes will be generated automatically.
Also provide a 512-pixel PNG and, if possible, an SVG: modern browsers and systems prefer them, and you'll be covered everywhere.
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Convert a ICO