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ICO to GIF converter

Convert ICO images to GIF format

No watermarkFree & unlimited
All processing happens in your browser. No data is sent to any server.

GIF is the most universally readable image format there is, which is the whole argument for this pair: a .gif of your icon renders in an ancient forum, an email client from 2004 and a wiki that refuses anything unfamiliar. The cost is specific: the encoder quantises to a fixed 216-colour web-safe palette with no dithering, and it does not write a transparency block, so an icon with a cut-out background comes out on a solid black rectangle rather than clear.

Key facts about ICO to GIF converter

Key facts about ICO to GIF converter
Transparency is lostNo graphic control extension is written, so no palette index is flagged transparent. Icon alpha is discarded and those pixels read as black.
PaletteA fixed 6x6x6 cube in steps of 51, 216 entries padded to a 768-byte table. It is not computed from your icon, so brand colours shift to the nearest cube point.
Colour shift magnitudeUp to 25 values per channel. A blue of 0,102,204 maps cleanly, but an off-white of 250,250,250 snaps to pure white.
DitheringNone. Each pixel picks its nearest palette entry independently, which keeps icon edges crisp and avoids the speckle a dithered encoder adds.
Output sizeDominated by the fixed 792 bytes of header and colour table, so a 32x32 icon usually gives 800 to 900 bytes whatever it depicts.
AnimationNot possible here. One image descriptor is written, so despite GIF supporting animation this conversion always produces a single still frame.
Source entryA multi-size icon yields one GIF. The browser decoder picks which entry to expose and this page cannot override that choice.
Opens the resultLiterally everything: browsers back to the nineties, every email client, every chat application, wikis, forums and every image viewer shipped.

What happens to your file

Every byte of the GIF is produced in your browser. The icon is read through an object URL, decoded by the browser's own icon parser inside an Image element, and drawn onto a canvas created by this page. From there the page's own JavaScript does the rest: the nearest-colour search against the web-safe cube, the LZW compressor, and the writer that emits the GIF89a blocks. No WebAssembly module is fetched and no server call occurs.

About this tool

  1. 1

    Flatten first if the icon is transparent

    Composite it over the background colour you want, because this conversion will otherwise leave those pixels black.

  2. 2

    Add the icon

    Drop a .ico file on the target area or click to browse. Up to twenty per batch.

  3. 3

    Convert

    Press Convert. At icon dimensions the palette search covers a few thousand pixels, so it finishes instantly.

  4. 4

    Check the colours and save

    Compare side by side, looking at flat brand colours, then download the .gif or take converted-gif-files.zip.

Specs & compatibility
Input and outputTakes .ico only (image/x-icon) and returns .gif with the image/gif type; any other extension is refused before decoding.
Conversion pathICO to GIF runs in three steps: an <img> element decodes the icon and the browser picks one entry from a multi-size file; the pixels land on a 2D canvas in this tab; then getImageData feeds a palette mapper and an LZW encoder that live in the page.
Browser supportThe icon side decodes in Chrome, Edge, Firefox and Safari, while writing the GIF needs nothing from the browser, the encoder shipping inside the page.
Controls for this pairNo quality slider, GIF not being a lossy target here, so the max-dimension presets from 3840 down to 200 px are the only way to hold the GIF down in size against the ICO.
Batch, caps and namingTwenty ICO files per run at 500 MB each; one result downloads as a single GIF, several as converted-gif-files.zip, zipped by JSZip 3.10 in page memory.
Device ceilingThe canvas caps it: past roughly 16,384 px a side Chromium refuses the bitmap and iPhone Safari gives up sooner, so an oversized ICO fails before any GIF bytes exist.
  • Icon artwork suits the web-safe palette well, since it is usually built from a handful of flat colours already.
  • Because the 768-byte table is always written in full, a two-colour icon still makes a file near 800 bytes.
  • A GIF of a logo is the safest thing to paste into an old wiki or board that chokes on modern formats.
  • If a colour comes out subtly wrong it landed between cube points; nudging it to a multiple of 51 per channel makes it exact.
  • Fixed web-safe 216-colour quantisation
  • LZW compressor running in the page itself
  • GIF89a output with one image block
  • Twenty icons per run, zipped in the browser
  • Posting an application or site icon on a forum or wiki whose uploader only accepts GIF, JPEG and PNG.
  • Embedding a small mark in an email template where format support cannot be assumed.
  • Producing a maximally compatible icon image for a legacy system.
GIF does support transparency through a graphic control extension naming one palette index as see-through, but this encoder never writes that block, so every output pixel is opaque. A transparent canvas pixel reads back as zero in all channels, so the discarded alpha appears as black.
Only if they sit on the palette grid. The encoder uses a fixed cube of 216 colours at multiples of 51 per channel and picks the nearest for each pixel, so any colour can shift up to 25 values in a channel. Pure primaries, white and black are exact; off-whites and muted greys move most.
Usually, but not by much, since both files are small and the GIF carries a fixed 792 bytes before any pixel data. A 32 by 32 icon with a raw four kilobyte payload typically becomes 800 to 900 bytes, and a PNG would often beat that while keeping transparency.
No. The writer emits a single image descriptor and no frame timing, so the result is always a still. The entries inside an icon are alternative resolutions of one picture rather than animation frames, and the browser exposes only one of them to the page anyway.
The encoder maps each pixel to its nearest palette colour and nothing else. Dithering would scatter quantisation error into neighbours so gradients look smoother, but it also speckles flat areas and softens hard boundaries, the opposite of what icon artwork needs.

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