Convert 3GP to MP4

Convert old 3GP feature-phone videos to MP4 right in your browser. Free and private, with no upload, no size limit and no watermark.

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Drop your file here (.3gp)

🔒 Private by design: your files are processed locally in your browser and never uploaded to any server.

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What a .3gp file is actually carrying

3GP is 3GPP’s cut-down relative of the MP4 container, standardised when a video message had to travel through a mobile network measured in kilobits per second. The wrapper itself is close enough to MP4 that FFmpeg demuxes both with the same code path; its own input line names the whole family at once, mov,mp4,m4a,3gp,3g2,mj2. So the container is rarely what breaks.

The streams inside it are. A .3gp recorded on a feature phone typically holds H.263 or MPEG-4 Part 2 video next to AMR narrowband speech audio: codecs picked because a handset from that era could decode them in dedicated silicon, not because they would still be around two decades later. That combination is why the file opens as a black window, a stalled first frame, or sound with no picture on a current laptop, while the file size looks perfectly healthy. Nothing is corrupt. The decoders are simply gone.

Old codecs out, H.264 and AAC in

There is no repackaging shortcut here. Rewriting the container while keeping an H.263 stream inside would produce an MP4 that fails on exactly the same devices, so this tool decodes the picture and re-encodes it with libx264, and encodes the audio to AAC at 128 kbps. It also applies -movflags +faststart, which moves the MP4 index to the front of the file: that is what lets a browser or a messaging app begin playing before the whole file has arrived.

The output keeps your file’s own name with the extension swapped, so VIDEO0032.3gp comes back as VIDEO0032.mp4 rather than something generic you then have to rename.

Converting one recovered clip end to end

  1. Drop a single .3gp file onto the box above, or use Choose a file. Only the .3gp extension is accepted, and anything else you drop is listed straight back as an unsupported file type without being processed.
  2. Set Quality. The three entries map to constant-rate-factor values of 18, 23 and 28 in that order, where a lower number keeps more bits.
  3. Press Convert 3GP to MP4 and leave the tab open while the progress bar advances.

The first conversion in a browser session also has to fetch the FFmpeg WebAssembly core before any encoding begins, so that run starts with a pause later runs in the same session do not have.

Where the quality dropdown earns its place

The interesting thing about this particular conversion is how little the top setting buys you. Your source was compressed once already, at a low resolution, by an encoder with a tiny bit budget. Re-encoding at CRF 18 does not undo any of that; it just describes the existing softness and blocking in more detail and hands you a bigger file. Balanced sits at the point where the result is hard to tell from the source at full size, which for this kind of footage is where most people should stay.

Smaller file is worth reaching for when the clip is going into a message or an email rather than an archive. And if you want real control over the final size rather than a quality target, Compress Video is the next step: it accepts .mp4 only, so it runs after this page rather than instead of it.

Neighbouring jobs that do not need this page first

If all you actually want is the sound, an old voice message or a recording of someone who is no longer around, Convert Video to MP3 accepts .3gp directly and skips the video re-encode entirely. If your pile of legacy media is mixed rather than all 3GP, the general Video Converter takes 3GP alongside MTS, AVI, MKV and others, and can target WebM or GIF as well as MP4. Camcorder tapes specifically, the ones that arrive as .mts or .m2ts files, are handled by Convert MTS to MP4, which can often stream-copy instead of re-encoding because the video is already H.264.

Everything here runs through a WebAssembly build of FFmpeg inside the tab, single-threaded, on your own hardware. That is why there is no file-size ceiling and no queue, and also why a long clip takes real time rather than finishing instantly. Old 3GP footage is short and small by nature, so it is one of the easier things to convert this way.

Frequently asked questions

Can I convert several 3GP clips in one go?

No. This page takes one file per run, so a folder of old clips means repeating the run once per file. Download each finished MP4 before you reset the box for the next one, because resetting releases the download link the browser created for the result and it stops working.

Why is my converted MP4 larger than the 3GP I started with?

Re-encoding cannot recover detail, but it can happily spend more bits than the original did. At the High quality setting in particular, the encoder works hard to reproduce faithfully the compression artefacts already baked into an old H.263 stream, which is an expensive thing to describe accurately. Picking Smaller file (lower quality) usually brings the size back under the source. The box shows the before and after figures with a percentage once the run finishes, so you can see it happen.

Does the conversion change the resolution or frame rate?

No. The command sets a video codec, a quality value, an encoder preset, an audio codec and bitrate, and a fast-start flag. There is no scaling filter and no frame-rate argument anywhere in it, so a 176x144 clip comes back at 176x144 and the timing is carried over from the source. Upscaling a low-resolution phone clip would only invent pixels that were never recorded, which is why it is not offered.

What happens if I rename another video file to .3gp and drop it in?

The dropzone checks the extension only, so the file is accepted and handed to FFmpeg. What happens next depends on whether FFmpeg recognises the actual bytes. If it cannot decode them there is no output file to hand back, and the page ends on its single generic processing-failure message rather than naming the real cause. Renaming a file never changes what is inside it.

Can I stop a conversion that is taking too long?

Yes. A Cancel button sits under the progress bar while a run is in flight. It shuts the FFmpeg worker down and clears the box completely, so there is no partial MP4 kept and the file you had chosen is removed from the list. Cancelling means starting again from the file picker rather than resuming.

Is my original .3gp file modified or deleted?

No. The file you drop in is read into the page and used as input; the MP4 arrives as a separate download through your browser. The .3gp stays byte for byte where it was on disk. Keep it until you have confirmed the MP4 plays, since a re-encode is one-way and there is nothing to undo it with.

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