Step 1: Provide your WebM files using the button above or by toss and let go.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Fetch your converted 3GP files.
WebM to 3GP Conversion FAQ
How do I convert WebM to 3GP without re-encoding the video stream?
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There is no stream-copy switch on this page. A few pairs copy a compatible video stream into the 3GP container without re-encoding it, MKV to MP4 among them, which is quick and loses no quality. Most pairs re-encode the video. WebM is deliberately narrow: VP8 or VP9 video (AV1 more recently) with Vorbis or Opus audio, and nothing else. 3GP holds H.263 or MPEG-4 Part 2 video with AMR narrowband speech audio, all tuned for minimal bitrate rather than quality.
What happens to the subtitle tracks in my WebM file?
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They are dropped. 3GP has no soft-subtitle stream to hold them, and the converter neither burns them into the picture nor exports them as a separate file. If you need them, extract the subtitles to an .srt file with a desktop tool such as ffmpeg or MKVToolNix before converting, and load that file alongside the 3GP in your player. 3GP is capped at low resolutions and mono speech-grade audio; upscaling it will not restore detail that was never captured.
Can I still embed the file on a web page after converting WebM to 3GP?
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Not directly. WebM plays inline in every browser; 3GP does not, so a page embedding it falls back to a download link or an empty player frame. If the file is destined for a website, keep the WebM for the web and treat the 3GP as the archive or editing copy.
Both WebM and 3GP are modern containers — which should I actually keep?
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Keep whichever matches where the file is going, because neither is better in the abstract. One of these two is built for playback compatibility and the other for holding everything a file might contain, and they trade against each other exactly along that line. The pragmatic answer for most libraries is to archive in the feature-rich container and export to the compatible one on demand. WebM plays natively in every modern browser with no plugin, no licence fee and no patent exposure, which makes it the default for web-embedded video. 3GP files are tiny and decode on the weakest hardware imaginable, which is why feature phones and low-end handsets still record it.
Will multi-track audio survive WebM to 3GP conversion?
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Usually not. Most conversions keep one audio track, the one with the most channels (normally the main mix), re-encoded for the 3GP container, so commentary and alternate-language tracks are dropped. AVI, WMV, MPEG, FLV, VOB and M4V to MKV keep every track, and so does MP4 to MOV. To keep a different track, remux the WebM with that track first (VLC or ffmpeg can do this), then convert it. 3GP is the container the 3GPP standardised for early mobile phones, when video had to fit a 176x144 screen and a 2G data plan.
Are subtitle tracks preserved when converting WebM to 3GP?
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On some pairs. MP4 to MOV keeps every text subtitle track. AVI, WMV, MPEG, FLV, VOB and M4V to MKV keep every subtitle track: text subtitles are copied or converted to SRT, and picture-based subtitles such as DVD or Blu-ray ones are copied as they are. MP4, MOV and WebM to MKV keep only the first subtitle track (as ASS), and MP4 to WebM keeps the first one as WebVTT. Other pairs, including MKV to MP4 or MOV and WebM to MP4, drop subtitle tracks, and the converter does not burn them into the picture. Subtitles that are already burned in stay, because they are part of the video frames.
What about MKV attachments (fonts, cover art) when going WebM to 3GP?
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MKV is the only mainstream container that stores arbitrary attached files (TTF fonts for ASS subs, JPG cover art, fan-translated PDF inserts). Going from WebM to 3GP drops these attachments when 3GP is not MKV — the elementary streams convert, but the attached payload stays in the source. Keep WebM as a backup if you depend on attached fonts.
Which codec does the 3GP output use by default?
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It depends on the 3GP container. MP4, MOV and MKV output use H.264, which plays on practically every phone, browser and TV. WebM output uses VP9. AVI, WMV and MPEG output use the older codecs those formats were designed for.
How does HDR (HDR10, Dolby Vision) survive WebM to 3GP?
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There is no HDR processing or tone mapping. When the video stream is copied (MKV to MP4 or MOV with the default settings), HDR10 passes through as it is. When the video is re-encoded, the HDR10 mastering metadata is dropped and Dolby Vision or HDR10+ data is not kept, and with a Quality, Resolution or Frame Rate setting some pairs also reduce the video to 8-bit colour, so an HDR WebM can look washed out in the 3GP.
Why is my 3GP file smaller / larger than the WebM after conversion?
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It depends on what happens to the video. MKV to MP4 or MOV with the default settings copies the video stream unchanged, so the size stays close to the source. Most other pairs re-encode it: a high-bitrate WebM usually comes out smaller, while an already heavily compressed one can grow. Smaller File under Quality gives the smallest output, and H.265 in the Codec setting (MP4, MOV and MKV) is usually smaller than H.264 at similar quality but plays on fewer devices.
