Convert 3GP to MP4
Turn old phone 3GP files into MP4s that iPhones, Android phones, TVs and editors play, without uploading them.
- Nothing is uploaded
- Works offline after first visit
- Open source
- No watermark · limit is your device’s memory; phones hold less
Converts 3GP and 3G2 phone videos (H.263, MPEG-4 or H.264 picture, with AMR or AAC sound) to MP4 with H.264 video and AAC sound (MP3 in the few browsers that have no AAC encoder). It is free and needs no account, and your videos are not uploaded: everything runs in your browser on your device, and after one visit and a short wait the page works offline.
Done
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Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
3GP is the video format of pre-smartphone mobile phones. Anything recorded on a feature phone or sent by MMS in the 2000s was saved as a small .3gp file, and many of those clips are still sitting on old memory cards and backups. Current phones, computers and web forms often refuse to open them.
This page reads the 3GP in your browser, decodes the picture and sound, and writes a new MP4 with H.264 video and AAC sound, the combination that plays everywhere. The video inside a 3GP from that era (H.263 or MPEG-4) and its AMR speech sound are not formats a browser plays, so they always have to be re-encoded. Clips are small, so a conversion takes seconds.
The file never leaves your device. Family clips from an old phone are exactly what you should not hand to a stranger’s server just to change the wrapper, and here there is no upload to wait for and no copy kept anywhere.
A 3GP picture is tiny, often 176 × 144 or 320 × 240, so the MP4 is the same size and looks just as soft: converting cannot add detail that was never recorded. The MP4 can come out larger than the 3GP, because the picture is re-encoded at a high quality setting.
Which 3GP files this converts
- Picture: H.263, MPEG-4 Part 2 and H.264. H.264 is copied into the MP4 as it is; the other two are decoded and written as H.264.
- Sound: AMR (narrowband and wideband), the speech codec of every phone of that time, and AAC. AMR is converted to AAC at 48 kHz, or to MP3 in a browser with no AAC encoder (Chrome on Linux); AAC is copied as it is.
- Not converted: a 3GP whose picture or sound is another codec shows a message naming it, and nothing is converted. The page never leaves out the sound without saying so; tick Remove the sound to drop it on purpose.
What this page loads
Most video runs on your browser's WebCodecs through Mediabunny. For old formats the browser cannot read, the page loads a decoder built from FFmpeg's libraries (LGPL) only when you convert such a file.
For 3GP that module is about 1 MB (a few hundred KB compressed) and comes from stayput.dev, not from anyone else’s server. The licenses page links its exact source and how it was built.
How it works
- Drop one or more 3GP files, or tap to pick them.
- Tick Remove the sound if you only need the picture.
- Convert, then open or share the MP4. Several files download together as a zip.
In your browser, not on a server
Mediabunny (MPL-2.0), a media toolkit written in TypeScript, reads the MOV, MKV, WebM or MP4 container in your tab. H.264 video and AAC or MP3 sound are copied into the new MP4 packet by packet, which takes seconds and changes nothing in the picture. Other video (VP8, VP9, AV1) is decoded and re-encoded by your browser’s own video encoder through WebCodecs, H.264 where available, and other sound becomes AAC or Opus. An AVI, which no browser opens, is decoded in a background worker by a separate decoder module and re-encoded the same way. An FLV is opened by a small separate reader module, and its H.264 picture is copied into the MP4 as it is. Most video runs on your browser's WebCodecs through Mediabunny. For old formats the browser cannot read, the page loads a decoder built from FFmpeg's libraries (LGPL) only when you convert such a file. The MP4 is written in memory.
Compared with upload-based tools: Online converters upload the whole video just to rewrap it, which can take longer than the conversion itself, cap free files at 100 MB to 1 GB, and keep a copy on their server. Here the file never leaves your device, and a large MOV from your phone converts in seconds because nothing is re-encoded that does not need to be.
Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
How do I convert 3GP to MP4?
Drop the .3gp file on this page and press Convert. Your browser decodes it and writes an MP4 with the same name and a .mp4 ending. Nothing needs installing, and you can drop several files at once.
Will the sound be kept?
Yes. AMR sound, which is what most 3GP files hold, is converted to AAC, and AAC sound is copied. If a file’s sound is in a format this page cannot read, it says so and nothing is converted; tick Remove the sound to convert the picture alone.
Why is my MP4 so small and blurry?
Phones of that era recorded at 176 × 144 or 320 × 240 pixels with strong compression. The MP4 keeps that size and cannot add detail that was never captured.
Why does it say the picture is not supported?
A 3GP is only a wrapper. This page opens files with H.263, MPEG-4 or H.264 picture, and names any other codec it finds instead of failing without a reason.
Does a portrait phone video stay upright?
Yes. If the 3GP records that it should be turned, the MP4 carries the same turn flag, so players show it the right way up.
Is the 3GP uploaded anywhere?
No. The file is read from your disk in slices by code running in a background worker in your tab, and the MP4 is written in memory. The decoder module downloads from stayput.dev when you first convert, and it carries none of your data.
Is the file uploaded anywhere?
No. There is no server in this process. The page is a static file and the work is done by code running inside your browser tab. Give the page a short while after one visit to save itself for offline use; then you can turn off Wi-Fi and it still works.
More video and audio tools
Video to MP4
Turn MOV, MKV and WebM files into MP4s that play everywhere. Converted on this device, never uploaded.
Screen recorder
Capture your screen, one window or a tab, with its sound and your voice. The video is made in this tab and never uploaded.
Voice recorder
A voice memo, a voice-over or a quick demo, recorded in this tab and saved as MP3. The sound never leaves your device.
Volume booster
Boost a quiet recording, turn down a loud one, or even out a batch. Done on this device, never uploaded.
Other conversions
Guides
- How to convert MOV to MP4MOV plays fine on Apple devices but not everywhere else. Here is how to convert it on a Mac and on Windows.