What is the PARTIAL file format?
The .partial file extension is used for partially downloaded files by Internet Explorer 9 (and later) and the original (EdgeHTML) Microsoft Edge browser. As the name suggests, a .partial file stores only a part of the downloaded - or currently downloading - file. Since January 2020, Chromium-based Microsoft Edge switched to .crdownload files instead.
Temporary file
A .partial file is created when the download process is paused or canceled. The download process can be resumed by clicking the file in the browser's Downloads panel. .partial is only a temporary extension - it is removed when the download process is finished and the file size matches the expected total.
.partial files - mostly unusable
A .partial file as such is unusable. However, some files, such as audio or video files, can be played partially even if they are incomplete. The file's internal bytes reflect whatever has been received so far - a partial MP4 opens like a truncated MP4, a partial ZIP archive starts with valid ZIP header bytes.
.partial files are named after original files with an added random code and suffix - for example, audio.mp3.iqzox9.partial (where iqzox9.partial is the added code and suffix, and audio.mp3 is the original file name). After the download is complete, the browser automatically removes the appended compound part.
Security & safety
RISK: LOWA .partial file cannot execute and is exactly as risky as the file being downloaded - no more, no less. The suffix actually helps: it stops the OS from treating an incomplete executable as runnable, which is part of its purpose. Two practical notes: if you didn't initiate the download that created the .partial, treat the underlying source file as suspicious and delete it; and orphaned .partial files left from old or cancelled downloads are safe to delete to reclaim disk space. Do not reinstate the retired Internet Explorer just to handle one - re-download in modern Edge instead.
Format details
in a nutshellPrograms that open PARTIAL files
Windows3 apps
VLC media player
Open-source For partial video/audio only: drag the .partial into VLC to play the portion that downloaded. 
Microsoft Edge (re-download)
Built-in Open Edge (the modern replacement for IE), press Ctrl+J for Downloads, and re-download the file from the original link; modern Edge can't resume an old IE .partial directly.
Internet Explorer mode (legacy)
Built-in If you still have the original IE download entry, retry it; otherwise restart the download. IE itself is retired - use Edge. Technical details
deep spec| Developer | Microsoft (Internet Explorer / legacy EdgeHTML Edge) |
| Associated OS | Windows |
| MIME type | application/octet-stream |
| File structure | Raw truncated prefix of the target file - no wrapper, container, or signature of its own |
| Magic bytes | None of its own; the leading bytes match the file being downloaded (e.g., a partial MP4 begins with MP4 header bytes) |
| Typical file size | 0 bytes up to the full size of the target file; grows continuously as the download proceeds |
| Compression | None added - inherits any compression present in the underlying target file |
| Encryption | None added |
| Naming convention | Original filename + random alphanumeric code + `.partial` suffix (e.g., `audio.mp3.iqzox9.partial`) |
| Browser support | Internet Explorer 9 (2011) through legacy EdgeHTML Microsoft Edge (2015-2020) |
| Superseded by | Chromium-based Microsoft Edge (since January 2020) uses `.crdownload` instead of `.partial` |
| Resume behavior | An interrupted download can be resumed from the browser's Downloads panel; the existing `.partial` file continues to grow from where it stopped |
| Completeness check | Browser compares the downloaded byte count against the expected Content-Length before renaming the file and removing the `.partial` suffix |
| Equivalent formats | `.crdownload` (Chrome / Chromium Edge), `.part` (Firefox), `.download` (Safari / macOS), `.opdownload` (Opera) |
| Released | Internet Explorer 9 (2011); used by IE and the original (EdgeHTML) Microsoft Edge until the 2020 Chromium switch |
| Latest version | N/A - staging convention, not a versioned format |
PARTIAL conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about PARTIAL files.
