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PART MP4
File conversion

Convert PART to MP4

Verified by Adam B.· reviewed by FE Editorial ·updated Jul 26, 2026
QUICK ANSWER
Is it possible to convert PART to MP4?
Yes - PART converts to MP4.

Resume or complete the download in Firefox or your download manager - the .part file already contains MP4 data and Firefox renames it automatically when the transfer finishes. If only part of the file arrived, the missing video footage cannot be recovered by any software.

Also to MP4: AVCHD · USM · MXF

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Tested on macOS, Windows & Linux
Last verified Sep 2026

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Why convert PART to MP4?

A .part file is not a separate format - it is an in-progress download sitting on disk under a temporary staging name used by Firefox, wget, aria2, and other download managers while the transfer is active. The .part suffix is the only thing preventing the file from being recognized as MP4; the video data inside is unchanged.

How to convert PART to MP4

Mozilla Firefox FREE

Press Ctrl+J (Windows/Linux) or Cmd+J (macOS) to open the Downloads panel, find the interrupted item, and click the resume arrow. Firefox renames filename.mp4.part to filename.mp4 automatically when the download reaches 100%.

VLC FREE

Drag the .part file into VLC to play the bytes that arrived so far; VLC stops at the point where the download was cut off. This does not recover missing footage - it only lets you view what is already on disk.

JDownloader FREE

Reload the original link in JDownloader's queue and click Resume; JDownloader handles interrupted downloads and continues from where the .part file left off.

About these formats

.PART Partial Download File

A PART file is a temporary file a downloader writes while data is still arriving. Firefox saves an active download as "filename.ext.part" and renames it to the real name only when the…

Open .PART details →
.MP4 MPEG-4 Part 14 Video File

An MP4 file is a video container (MPEG-4 Part 14, standardized 2003) that holds video, audio, subtitles, and chapters in one file. It plays on every phone, computer, browser, and smart TV…

Open .MP4 details →

Quality & what to watch

  • If the .part file size matches the expected file size, rename it by removing the .part suffix - the MP4 is complete and playable without any conversion.
  • A truncated .part file whose download was interrupted contains only the bytes that arrived; missing video frames cannot be reconstructed by any software.
  • Resume works only if the download entry is still listed in the browser or download manager and the server supports HTTP range requests.

Frequently asked questions

Can I play the partial file while it is still downloading?
VLC can play the portion already on disk but stops where the download was cut off.
The download shows 100% but the file still has `.part` in the name - what happened?
Firefox occasionally fails to rename the file due to antivirus or permissions; check the file size and, if it matches, rename it manually to .mp4.
Is there a converter that can repair a truncated MP4?
No - a converter cannot insert bytes that were never downloaded; the only fix is resuming or restarting the download.