Free online MKV to 3GP converter
Convert MKV video into a compact 3GP file for legacy phones and embedded players.
Convert MKV to 3GP online - free
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How it works
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Upload your .mkv file
Click to browse to select your file you want to convert or simply drag & drop your file into selected area.
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Perform .mkv to .3gp conversion
After successful file upload, click to convert when you are ready.
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Download converted .3gp file
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How to convert mkv to 3gp file
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An older mobile phone, multimedia messaging system, or embedded player may accept .3gp but reject MKV. Converting creates a smaller, lower-bandwidth copy when you reduce the resolution, frame rate, and bitrate for the target device.
What the MKV format is
MKV, or Matroska Video, is an open multimedia container that can store video, multiple audio tracks, subtitles, chapters, attachments, and metadata in one file. It does not specify a single codec: an MKV may contain H.264, H.265/HEVC, VP9, AV1, MPEG-4, or other streams.
MKV is common in OBS Studio recordings, disc backups made with MakeMKV, FFmpeg and HandBrake exports, screen recordings, and downloaded video releases. A computer media player may support the container while a phone or editing application rejects it because of the codecs, stream structure, resolution, or file size.
What the 3GP format is
3GP is a compact multimedia container created for 3G mobile networks and older phones. Typical video codecs are H.263 and MPEG-4 Part 2; some 3GP devices also support H.264. Common audio codecs include AMR-NB, AMR-WB, and AAC.
3GP files use modest resolutions and bitrates, which reduces storage and bandwidth requirements. Use this format when the receiving phone, messaging system, or embedded player specifically requires .3gp. Modern phones, browsers, and media players generally support MP4 more reliably than 3GP.
Convert the file on 101convert.com
- Open the MKV-to-3GP converter on 101convert.com.
- Select the MKV file from your device.
- Choose
3GPas the output format and start the conversion. - Download the resulting
.3gpfile and test it on the destination device.
This option requires no installed software and is free to use. Do not upload confidential material unless the service's file handling and retention terms are acceptable.
Convert with FFmpeg
FFmpeg provides more control over codecs, dimensions, streams, and bitrate. Inspect the source before converting:
ffprobe -hide_banner input.mkv
For a 3GP file using MPEG-4 Part 2 video and AAC audio, run:
ffmpeg -i input.mkv -map 0:v:0 -map 0:a:0 -c:v mpeg4 -vtag mp4v -vf "scale=320:240:force_original_aspect_ratio=decrease,pad=320:240:(ow-iw)/2:(oh-ih)/2" -r 15 -b:v 350k -c:a aac -ar 8000 -ac 1 -b:a 32k output.3gp
This selects the first video and audio streams, fits the image inside 320×240 without distortion, limits video to 15 frames per second, and applies low audio and video bitrates. Change these values to match the phone's documented limits. The -map options discard additional audio tracks, subtitles, chapters, and attachments.
Some very old phones require H.263 video and AMR-NB audio instead. If the installed FFmpeg build includes the AMR-NB encoder, a low-resolution legacy command is:
ffmpeg -i input.mkv -map 0:v:0 -map 0:a:0 -c:v h263 -vf "scale=176:144:force_original_aspect_ratio=decrease,pad=176:144:(ow-iw)/2:(oh-ih)/2" -r 10 -b:v 128k -c:a libopencore_amrnb -ar 8000 -ac 1 -b:a 12.2k output.3gp
If FFmpeg reports that libopencore_amrnb is unavailable, use AAC if the phone supports it or install a build containing that encoder. H.263 and AMR-NB may improve compatibility with legacy hardware but normally produce lower quality than MPEG-4 Part 2 and AAC.
Quality and compatibility limits
Re-encoding is usually required because MKV streams often use codecs, resolutions, or bitrates that do not fit the 3GP device profile. Re-encoding loses quality, and reducing a video to 176×144 or 320×240 permanently removes detail.
A .3gp extension does not guarantee compatibility. The target device may impose separate limits for video codec, codec profile, resolution, frame rate, audio codec, sample rate, channel count, bitrate, file size, and filename length. Follow the device manual instead of assuming that every 3GP player supports every permitted stream combination.
Burn subtitles into the video before conversion if they must remain visible; ordinary subtitle tracks and embedded attachments are commonly discarded. Keep the original MKV until the converted file has been tested on the actual phone or player.
MKV vs 3GP: format comparison
How the MKV and 3GP formats compare on the properties that matter most for this conversion.
| Property | .MKV Matroska Video | .3GP 3GPP multimedia file |
|---|---|---|
| Format type | Container | Container |
| Compression | Both | Both |
| Maximum resolution | 8K and above | HD (1080p) |
| Audio tracks | Multiple | Multiple |
| Subtitles | Embedded in the file | Embedded in the file |
| Streaming | Partial | Partial |
| Opens in a web browser | No | Partial |
| Typical file size | Large | Small |
| Open standard | Yes | Yes |
| Introduced | 2002 | 1998 |
| Developer | Matroska org | 3rd Generation Partnership Project (3GPP) |
| MIME type | video/x-matroska | video/3gpp |
Suggested software and links: mkv to 3gp converters
Frequently asked questions
Is the MKV to 3GP converter free?
Yes, converting MKV to 3GP on 101convert.com is completely free. No registration, email address or installation is required. If you need a higher file size limit or want to convert more files at once, see our plans.
How large can my MKV file be?
You can upload MKV files up to 2000 MB and convert up to 1 files at once in a single batch.
What happens to my uploaded files?
Files are processed automatically and deleted from our servers within a few minutes after conversion. We never view or share your files.
Do I need to install any software to convert MKV to 3GP?
No. The MKV to 3GP conversion runs entirely online in your browser and works on Windows, Mac, Linux, Android and iPhone.
Did the conversion fail?
In most cases, the cause is an incorrect file format. Please upload a valid MKV file for this MKV to 3GP conversion. Occasionally, the issue may be on our side. We analyze recurring conversion failures and disable or fix the converter if we detect a defect.
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