Free, no account, no watermark. Your ICO files are turned into AVIF inside this browser tab — they are never uploaded to a server.
Nothing leaves your device
No account, no email
Free, and no watermark
Drop your files here
Tap to pick your photos
or
Choose files
Up to 30 files at a time · 60 MB per file
Higher quality means a larger file.
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Why convert ICO to AVIF?
The lightest possible result, though usually more precision than an icon needs. Icons are small to begin with, so the absolute saving over PNG is measured in kilobytes rather than megabytes. It makes sense when the icon is part of a page you are optimising thoroughly, and transparency is preserved either way.
AVIF is the pick when bandwidth matters most and your audience is on current browsers. A hero image can often be cut to a third of its JPEG size with no visible difference.
How to convert ICO to AVIF
Drop your ICO files into the box above, or click to pick them from your device.
Adjust the quality slider if you want a smaller file or a sharper result.
Hit convert. The work happens inside your browser, so it takes a second or two per image.
Download each AVIF file, or grab them all in one ZIP.
About the formats
ICO — Windows Icon
ICO is a container for icons rather than a general image format. A single .ico can hold the same icon at several sizes so Windows can pick whichever one it needs, and modern files often just wrap PNG data inside. Browsers still accept it for favicons, but nothing else treats it as a normal picture.
Strengths
Holds several sizes in one file, so icons stay crisp at any scale
The historical standard for Windows icons and website favicons
Modern files can carry PNG data with full transparency
Limitations
Not a general-purpose image format, and never was
Most image editors cannot open or export it
Size limits make it useless for photographs
AVIF — AV1 Image File Format
AVIF is the newest format here, built on the AV1 video codec. It beats WebP by another 20–30% on size, handles HDR and wide colour gamut, and supports transparency and animation. Encoding is slow and desktop support is still patchy, but for images delivered over the web it is the most efficient option browsers actually understand.
Strengths
The smallest files of any format with real browser support
HDR and 10-bit colour, so gradients do not band
Transparency and animation included
Limitations
Slow to encode compared with JPEG or WebP
Older browsers and most desktop applications cannot open it
Editing software support remains thin
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Frequently asked questions
Are my photos uploaded anywhere?
No. The conversion runs entirely in your browser using WebAssembly and the Canvas API. Your images are never sent over the network, never touch a server, and are dropped from memory as soon as you close the tab.
Will I lose quality?
AVIF is a lossy format, so some data is discarded. At the default quality of 85% the difference is invisible on screen for most photos. Raise the slider if you plan to print or edit the result.
Is there a limit or a cost?
It is free and there is no account. The only limits are practical: 30 files at a time and 60 MB per file, so that the tab does not run out of memory on a phone.
Can I convert several files at once?
Yes — drop in up to 30 files and they are processed one after another, then downloaded individually or as a single ZIP.
Does it work offline?
Once the page has loaded, yes. The converter itself needs no network connection, so you can drop the connection and keep converting.
Does it work on a phone?
Yes, on iOS and Android. Large batches are slower on a phone because the decoding happens on the device, so stick to smaller groups if things feel sluggish.