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?
+
When the WebM and 3GP containers can both carry the same codec (H.264, H.265, VP9, AV1), the converter falls back to a remux: the elementary streams are copied byte-for-byte into the 3GP container and only the wrapper changes. A remux of a 1 GB WebM into 3GP typically finishes in 5-15 seconds with zero quality loss. 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?
+
They cannot stay selectable, because 3GP has no soft-subtitle stream to hold them. There are two ways out: burn them into the video during conversion, which makes them permanent and unstyleable, or export them as a separate .srt alongside the 3GP for the player to load. The converter tells you which it did rather than dropping them silently. 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?
+
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.
What happens to 5.1 surround audio when converting WebM to 3GP?
+
It is downmixed to stereo, because 3GP has no dependable multichannel path. The fold-down uses the standard ITU coefficients so dialogue in the centre channel stays intelligible and the surrounds come in at reduced level rather than vanishing. Anything that relied on discrete channel placement is gone after that.
Both WebM and 3GP are modern containers — which should I actually keep?
+
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?
+
Yes — every audio track in the WebM (director commentary, alternate languages, descriptive audio) is preserved in the 3GP when the target container supports multi-stream audio. MKV and MOV handle unlimited audio tracks; MP4 supports many but some hardware players only see track 1; WebM is capped at one Opus / Vorbis track. 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?
+
Soft subtitles (selectable tracks) survive when 3GP can carry them: MKV holds SRT, ASS, SSA, PGS, VobSub natively; MP4 only holds mov_text (a stripped-down format). Converting an MKV with ASS styled subs to MP4 will typically downgrade them to mov_text or burn them in. Hardsubs (burned into the video) carry over regardless.
Does WebM to 3GP keep chapter markers / DVD-style navigation?
+
Chapter metadata transfers between WebM and 3GP whenever both containers support a chapter atom (MKV, MP4, MOV). WebM stores chapters in a Matroska-compatible block, so MKV <-> WebM chapters round-trip cleanly. AVI has no chapter spec at all, so an AVI source arrives with no chapters to carry across and an AVI target cannot store the ones it was handed; add markers manually afterwards if you need them.
What about MKV attachments (fonts, cover art) when going WebM to 3GP?
+
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?
+
The default codec is chosen to match the 3GP container conservatively: MKV defaults to H.265 (HEVC) for better compression; MP4 defaults to H.264 for the widest device support; WebM defaults to VP9; AVI uses MPEG-4 ASP (DivX/Xvid lineage). Override via the advanced codec dropdown — AV1 is available for MKV / WebM where you want maximum compression and can wait through the encode.
How does HDR (HDR10, Dolby Vision) survive WebM to 3GP?
+
HDR static metadata (HDR10 mastering display values, max content light level) carries through to 3GP when both containers and the chosen codec support it (HEVC, AV1 in MKV / MP4). Dolby Vision is more fragile — DV profile 5 / 7 / 8.1 in WebM commonly survives only into MKV with HEVC; converting to a 3GP container that does not carry the DV layer flattens to HDR10.
Will the WebM to 3GP converter keep variable framerate (VFR)?
+
MKV and WebM record real per-frame timestamps and handle VFR natively, so WebM VFR survives into a 3GP of those formats with no resampling. MP4 nominally stores timestamps too but some players assume CFR; the converter exposes a "force CFR" toggle that resamples VFR WebM to 24 / 30 / 60 fps 3GP for problematic targets.
