Step 1: Provide your 3GP 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 MP4 files.
3GP to MP4 Conversion FAQ
How do I convert 3GP to MP4 without re-encoding the video stream?
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When the 3GP and MP4 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 MP4 container and only the wrapper changes. A remux of a 1 GB 3GP into MP4 typically finishes in 5-15 seconds with zero quality loss. 3GP holds H.263 or MPEG-4 Part 2 video with AMR narrowband speech audio, all tuned for minimal bitrate rather than quality. Almost every MP4 in the wild is H.264 video with AAC audio; the container also legally holds HEVC, AV1 and VP9.
Can 3GP be converted to MP4 without re-encoding the video?
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Yes, and it is the fast path. 3GP and MP4 share the same underlying box structure, so the video and audio streams are copied across byte-for-byte and only the container wrapper is rewritten. Nothing is decoded and nothing is re-compressed, so a feature-length file finishes in under a minute instead of half an hour, with output quality identical to the source. 3GP is the container the 3GPP standardised for early mobile phones, when video had to fit a 176x144 screen and a 2G data plan. MP4 is ISO/IEC 14496-14, standardised in 2001 and derived from the same QuickTime box layout MOV uses.
Can I add selectable subtitles once the file is MP4?
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Yes. 3GP has no usable soft-subtitle track, so subtitles for 3GP content had to be burned into the picture or shipped as a separate sidecar file. MP4 carries subtitles as their own selectable stream, so after conversion you can attach an SRT track the viewer can switch on, switch off or restyle.
Will the MP4 play in a browser when the 3GP would not?
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Yes, and that is usually the whole reason for the conversion. A 3GP embedded in a web page either shows a broken player or forces a download, because browsers ship no decoder for it. MP4 plays inline through the native HTML5 video element with no plugin and no external application. MP4 is the safest possible delivery target — every phone, browser, console, editor and Smart TV built in the last decade plays it without extra software.
Will multi-track audio survive 3GP to MP4 conversion?
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Yes — every audio track in the 3GP (director commentary, alternate languages, descriptive audio) is preserved in the MP4 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.
Are subtitle tracks preserved when converting 3GP to MP4?
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Soft subtitles (selectable tracks) survive when MP4 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 3GP to MP4 keep chapter markers / DVD-style navigation?
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Chapter metadata transfers between 3GP and MP4 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 3GP to MP4?
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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 3GP to MP4 drops these attachments when MP4 is not MKV — the elementary streams convert, but the attached payload stays in the source. Keep 3GP as a backup if you depend on attached fonts.
Which codec does the MP4 output use by default?
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The default codec is chosen to match the MP4 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. MP4 only supports one widely-honoured subtitle format (mov_text), and multi-track audio is unreliable outside desktop players.
How does HDR (HDR10, Dolby Vision) survive 3GP to MP4?
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HDR static metadata (HDR10 mastering display values, max content light level) carries through to MP4 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 3GP commonly survives only into MKV with HEVC; converting to an MP4 container that does not carry the DV layer flattens to HDR10.
Will the 3GP to MP4 converter keep variable framerate (VFR)?
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MKV and WebM record real per-frame timestamps and handle VFR natively, so 3GP VFR survives into an MP4 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 3GP to 24 / 30 / 60 fps MP4 for problematic targets.
Why is my MP4 file smaller / larger than the 3GP after conversion?
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Same-codec remux produces a near-identical size (container overhead differs by 0.1-2%). A codec change can swing the size by 50% or more: H.264 to H.265 typically halves the file at the same visual quality; H.264 to AV1 halves it again on a slow preset. Going from a high-bitrate 3GP (Blu-ray rip) to a low-bitrate MP4 (web upload) is the most common reason for a dramatic drop.
