ICO is a Windows icon container that can hold several bitmap sizes and color depths in one file.
What this converter actually supports
Published still-image routes use the deployed ImageMagick and Ghostscript toolchain, with dedicated workflows for animation, camera RAW rendering, SVG tracing, and selected modern formats where the generic path is not sufficient.
Convert ICO to PNG to inspect an icon, or create ICO from a suitable square source for Windows and favicon use.
The public upload limit is 1 GB. Convertr does not reduce dimensions, duration, resolution, or output quality merely to manage worker load.
Quality and format limits
PNG and TIFF are useful lossless working targets. JPG is lossy and removes transparency; WebP and AVIF may be lossy or lossless. Preserve source pixel dimensions unless resizing is intentional.
Generic conversion may select one embedded size; use a dedicated favicon workflow when a multi-size icon set matters.
Published ICO inputs
These links come from the active conversion catalog, not from a generic list of possible formats.
Check that the file opens in its original application, is not encrypted or DRM-protected, and really matches its extension. A damaged header, unsupported internal codec, missing linked asset, or mislabeled file can fail even when ICO is generally supported. Try a different published target only when it fits your goal; changing the extension by hand does not convert the file.