ICO Converter
Convert any image to ICO in your browser. You get a multi-size ICO with PNG-compressed icons (16, 32, 48 and 256 px by default). ICO is best for favicons and Windows icons. Batch convert any number of files; nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
JPG, PNG, WebP, HEIC, AVIF, GIF, TIFF, SVG, RAW, PSD, JXL, BMP, ICO and more
How to use Convert to ICO
- 1
Drop your images or click to choose them. You can also paste from the clipboard.
- 2
ICO is written losslessly, so there is no quality to set.
- 3
Click Convert. Each file is processed on your device in a background thread.
- 4
Download files one by one or all at once as a ZIP.
Why use Aback Images for convert to ico
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
Fast batch conversion
Several files are converted in parallel worker threads, with per-file progress and cancel.
Content-checked input
Files are identified by their bytes, not their name, so a mislabelled file still converts correctly.
Real control when you want it
Resize, rotate, background colour, metadata and codec options sit under More options.
About Convert to ICO
About ICO
ICO is a container that bundles several sizes of the same icon (16, 32, 48, 256 px) into one file. It is still the most compatible format for website favicons and Windows app icons.
An ICO starts with a 6-byte ICONDIR (type 1 for icons) and a 16-byte entry per image giving width, height, colour count and offset. Each image is either a BMP without its file header plus an AND mask, or a complete PNG.
Strengths: Multiple sizes in one file; Required by Windows and supported by every browser as a favicon.
Drawbacks: Max 256×256 per image; Not for photos.
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Convert between 34 image formats in bulk: HEIC, WebP, AVIF, JPEG XL, PNG, JPG, GIF, TIFF, SVG, ICO, PSD, RAW and more.
Frequently asked questions
Which icon sizes are included?
16, 32, 48 and 256 px by default, the set Windows and browsers expect. You can choose other sizes. Non-square images are centred on a transparent square.
Which apps open ICO files?
Every browser (as a favicon), Windows and most Linux desktops.
Which formats can I convert from?
Anything this site can read: JPG, PNG, WebP, AVIF, HEIC, GIF, SVG, TIFF, BMP, ICO, JPEG XL, PSD, RAW and more. Files are identified by their bytes, so a mislabelled file still converts.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.