QT to MP4 Converter

Convert QuickTime files (.qt and .mov) to MP4 in your browser. The tool copies your video when MP4 can hold it and re-encodes only what it cannot. Nothing is uploaded.

How to convert

Convert QT to MP4 and keep the quality

A QT file is a QuickTime movie. The .qt extension is the older one, and Apple devices, cameras and screen recorders now use .mov for the same format. Both open in QuickTime Player, but many Windows and Android apps, websites and video editors expect an MP4.

This tool reads the header of your file first to see what is inside. If the video is H.264 or H.265 and the audio is AAC, it copies both into an MP4 without touching them. That takes seconds and loses nothing. If a stream cannot go into an MP4, such as PCM audio or ProRes video, only that stream is converted.

What happens to each kind of QT file

The table lists the streams the converter meets most often and what it does with them in the default mode.

Inside the fileWhat the converter doesWhy
H.264 video with AAC audioCopies bothMP4 holds both as they are. Screen recordings and many camera files look like this.
H.265 (HEVC) video with AAC audioCopies both and sets the hvc1 tagRecent iPhones record this. Apple devices and current browsers play it, older players may not.
H.264 or H.265 video with PCM audioCopies the video, converts the audio to AACffmpeg refuses to write PCM audio into an MP4 file.
Apple ProRes videoRe-encodes it to H.264ffmpeg cannot write ProRes into an MP4 file.
Animation, PNG, Photo JPEG, Cinepak, Sorenson and other old codecsRe-encodes them to H.264MP4 players do not support these codecs.
Timecode, chapter and caption tracksLeaves them outThe converter writes the video and audio tracks only.
Video with a transparent backgroundRe-encodes it and drops the transparencyH.264 has no alpha channel.

QT, MOV and MP4: what is the difference?

QT and MOV are the same QuickTime file format with different extensions. MP4 is built on the same box structure, which is why a straight copy is possible at all. What differs is the list of codecs each one allows. MP4 players expect H.264, H.265 or AV1 video and AAC or MP3 audio, while a QuickTime file can also carry ProRes, Animation or PCM audio.

Apple’s support page says you can rename a .mov file to .mp4 if its video codec is H.264. A rename does not change anything inside the file, and the index often stays at the end, which slows down playback on the web. The converter writes a new MP4 with the index first.

Convert QT to MP4 with ffmpeg

This page runs ffmpeg in your browser, and every file card shows the exact command. For a QT file with H.264 video and AAC audio it looks like this. You can run the same command on your own computer.

Default mode, nothing is re-encoded

ffmpeg -y -i input.mov -map 0:v:0 -map 0:a -c:v copy -c:a:0 copy -write_tmcd 0 -movflags +faststart output.mp4

Re-encode to H.264, balanced quality

ffmpeg -y -i input.mov -map 0:v:0 -map 0:a -c:v libx264 -preset veryfast -crf 23 -pix_fmt yuv420p -vf 'scale=trunc(iw/2)*2:trunc(ih/2)*2' -c:a:0 copy -write_tmcd 0 -movflags +faststart output.mp4
  • -c:v copy copies the video stream without decoding it.
  • -movflags +faststart writes the index at the start of the file so it can play while it loads.
  • -write_tmcd 0 leaves out the timecode track some QT files carry.

What to expect with large files and phones

Memory

Your browser reads the QT file from disk as needed, but the finished MP4 is built in memory. In our tests a 1.9 GB file converted on a computer with 16 GB of memory. The browser cannot build one file much larger than 2 GB, so a copy of a bigger file fails, while a re-encode to a smaller MP4 can still work. Close other tabs before you start a big file.

Speed

Copying takes seconds. Re-encoding runs on one processor thread inside the page, so it is slower than a desktop app. On an Apple M1 Mac, a 10-second 1080p clip took about 20 seconds to re-encode and a 20-second 720p clip about 18 seconds. Older laptops and phones are slower.

Privacy

Your files never leave your device. The converter itself, about 32 MB, is downloaded once from a public CDN, and your browser keeps it afterwards.

How the QT to MP4 converter works

Your browser reads the header of the QuickTime file, which lists every track and the codec it uses. The converter compares each track with what an MP4 file can hold. Video and audio that fit are copied byte for byte, which is why the default mode is fast and keeps the quality. A track that does not fit, such as PCM audio or ProRes video, is converted to AAC or H.264.

ffmpeg does the work. It is compiled to WebAssembly and runs inside the page, so your browser reads the file from your disk and nothing is sent to a server. The index of the new MP4 is written at the start of the file, so it can start playing before it has fully loaded.

If you choose Re-encode, the video is rebuilt with the x264 encoder at the quality you pick, and you can limit the picture height. The result plays on almost every device, at the cost of time and a small loss of detail.

How to convert a QT file to MP4

1

Add your files

Drop .qt or .mov files on the box, or choose them from your device. The tool reads each file and shows what is inside.

2

Check the plan

Every file lists what will happen to its video and audio. Keep the default unless you need H.264 or a smaller picture.

3

Convert

Press Convert. The first run downloads the converter, so it starts a little slower.

4

Download the MP4

Save each file on its own, or take all of them in one ZIP.

Example Usage

The video stream is copied without a change. Only the PCM audio is converted, because MP4 cannot hold it. That is why the file gets smaller.

Input
interview.qt: 5 minutes, H.264 video, PCM audio, 407.6 MB
Output
interview.mp4: the video is copied, the audio becomes AAC, 357.2 MB

Frequently Asked Questions

What is a QT file?
A QT file is a movie in Apple’s QuickTime format. It can hold video, audio and other tracks such as timecode. The .qt extension is the older one. Newer files from Apple devices, cameras and screen recorders use .mov for the same format.
Is a QT file the same as a MOV file?
Yes. Both use the QuickTime file format, and this converter reads both. Only the extension differs. What matters for playback is the codec inside, such as H.264, H.265 or ProRes.
Is this a quart converter?
No. QT on this page stands for QuickTime. If you want to convert quarts to liters, ounces or gallons, you need a volume converter, not a video tool.
Will I lose quality when I convert QT to MP4?
Not in the default mode. If your video is H.264 or H.265, the tool copies it into the MP4 without decoding it, so every frame stays the same. Quality drops a little only when the picture is re-encoded. That happens when you choose Re-encode to H.264, or when the codec cannot go into an MP4, as with ProRes.
Can I just rename a .qt or .mov file to .mp4?
Sometimes. Apple’s support page says a rename works when the video codec is H.264. A rename changes nothing inside the file, so files with other codecs, or with PCM audio, can fail to play. The converter checks every track and writes a proper MP4.
Can QuickTime Player export an MP4?
No. According to Apple’s QuickTime Player guide, File > Export As saves a QuickTime movie (.mov) with H.264 or HEVC video. To get an MP4, use a converter such as this one.
Why does the MP4 from my iPhone not play on my PC?
Recent iPhones record H.265 (HEVC). The converter copies it as it is, and some Windows PCs need the HEVC video extension from Microsoft to play it. Choose Re-encode to H.264 to get a file that plays on almost any device.
Does the MP4 keep a transparent background?
No. H.264 video has no alpha channel, so transparent areas become a solid colour, usually black. If you need transparency, use a format that supports it, such as WebM or ProRes 4444.
Is my video uploaded to a server?
No. Your browser reads the file from your disk, and ffmpeg, compiled to WebAssembly, converts it inside the page. The only download is the converter itself, about 32 MB, which your browser keeps for next time.
How big can the file be?
The input is read from disk as needed, but the MP4 is built in memory, so the limit depends on your device. In our tests a 1.9 GB QT file became an MP4 of the same size on a computer with 16 GB of memory. The browser cannot build a single file much larger than 2 GB, so copying a bigger file fails. Files over 2 GB can still be read, so re-encoding them to H.264 with a smaller picture gives a smaller MP4 and works.
Can I convert more than one file at a time?
Yes. Add up to 20 files. They convert one after another with the same settings. You can download each MP4 or all of them in one ZIP.
Does the MP4 keep the GPS location of my iPhone video?
In our tests it did not. We converted QuickTime files with a GPS tag and a device name, and neither appeared in the MP4. Text tags such as a title do carry over. If privacy matters, check the result with a metadata viewer.
Does it work on a phone or tablet?
The page opens on phones and tablets, but they have much less memory than a computer, so large files are more likely to fail there.

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The QT to MP4 Converter is maintained by CodeItBro. We aim to provide the best free developer tools on the web. If you have feedback or suggestions, please visit our contact page.

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