MKV to 3GP Converter

Convert MKV to 3GP: What This Tutorial Covers

This page re-encodes a Matroska (.mkv) video into 3GP, the compact container 3GPP defined for 3G mobile phones. It is written for the narrow set of people who genuinely need 3GP in 2026 — feeding an actual feature phone, an MMS gateway, or an embedded device that only ingests .3gp — and it is honest about the trade-offs: 3GP squeezes video down to phone-era resolutions and bitrates, and it cannot carry MKV's subtitle tracks, chapters, or multiple audio streams, so the output will be smaller, softer, and stripped of those extras. If you just want a smaller MKV that plays everywhere, you almost certainly want MKV to MP4 instead, not this page.

How to Convert MKV to 3GP

1. Upload Your MKV File: Drag and drop, or click "Add Files", to select one or more .mkv videos. Batch is supported, so a folder of clips runs in a single job.
2. Pick the Video Codec: Open Advanced Options and choose the Video Codec. The default is H.264, which gives the best quality at 3GP's low bitrates and is read by most post-2008 handsets; switch to H.263 or MPEG-4 only if you are targeting an older phone that predates H.264 support.
3. Set Resolution and File Compression (Optional): Use Preset Resolutions or Width x Height to drop the frame size to something a phone screen expects (176x144 or 320x240 are typical), and use Quality Preset or Specific file size to fit an MMS or storage limit. The Time Range trim panel lets you keep just one clip.
4. Convert and Download: Click Convert and download the .3gp. No sign-up, no watermark.

Walk-through: Codec, Resolution, and the Tracks MKV Will Lose

3GP is a low-bandwidth format, so the two settings that decide whether your file plays on the target device are the video codec and the resolution. Picking them to match the phone matters far more than chasing quality.

• Targeting a modern-ish phone (roughly 2009 onward): leave the Video Codec on H.264 and the audio on the default AMR (or switch audio to AAC if the device supports it). H.264 holds detail far better than the older codecs at the tiny bitrates 3GP uses.
• Targeting an old feature phone or an MMS gateway: set the Video Codec to H.263 or MPEG-4, keep audio on AMR Narrow Band, and drop the resolution to 176x144 (QCIF) or 320x240 (QVGA). Many early handsets only decode H.263 at QCIF, and an MMS gateway will often reject anything larger than a few hundred kilobytes.
• Targeting an embedded device or test harness: match whatever the device's documentation specifies. If it says "H.263 baseline, AMR-NB, QCIF," set exactly that — a higher-quality H.264 file may simply fail to open.

Two honest caveats specific to MKV. First, MKV is a flexible container that often holds several audio languages, soft subtitle tracks, and chapter markers; 3GP cannot carry any of that, so the conversion keeps one video and one audio track and discards the rest. If you need those subtitles, burn them in first or keep an MKV/MP4 copy. Second, this is a lossy re-encode: whatever codec the MKV uses (H.264, HEVC, VP9, AV1) is decoded and re-compressed into 3GP, which adds one fresh generation of lossy compression. You can only minimize that by not shrinking the resolution more than the target device needs.

Common Errors and How to Fix Them

• "The 3GP looks blocky and soft compared to my MKV" — Expected. 3GP targets phone-era bitrates and small resolutions, so detail is intentionally discarded to hit a tiny file size. If quality matters more than 3GP compatibility, convert to MKV to MP4 instead.
• "My subtitles and second audio track are gone" — Also expected. 3GP keeps a single video and single audio stream and has no place for MKV's soft subtitles, chapters, or extra languages. Pick the audio language you want before converting, and keep the MKV if you still need the extras.
• "My phone or MMS gateway rejects the file" — The codec or resolution is too modern. Switch the Video Codec to H.263, set audio to AMR Narrow Band, and drop the resolution to 176x144, which the widest range of legacy handsets accept.
• "The output is silent" — The source MKV may carry an audio codec the converter can't map to AMR, or you selected a subtitle/secondary track as the audio. Re-run with the Audio Codec set explicitly to AMR Narrow Band, or to AAC if the target device supports AAC audio in 3GP.
• "The file is still too big for MMS" — Shorten the clip with the Time Range trim panel, lower the resolution, and use Specific file size to cap the output; MMS payloads are often limited to a few hundred kilobytes.

When This Doesn't Work

If your MKV is corrupted (a truncated download, or a file copied off a failing disk) the converter can't re-encode it and the job will fail. And if you are reaching for 3GP only because you want a smaller video that still plays on current phones and computers, 3GP is the wrong target in 2026 — its codecs and resolution ceiling are dated, and you lose MKV's tracks for nothing. Use MKV to MP4 for a modern, well-compressed, broadly compatible file. 3GP earns its place only when something on the other end genuinely requires it. If you are instead trying to bring old phone footage out of 3GP into the flexible Matroska container, that is the reverse of this page — see 3GP to MKV.

Frequently Asked Questions

Why would I convert MKV to 3GP in 2026 instead of MP4?

Only when something on the receiving end actually requires 3GP — an older feature phone, an MMS gateway, an embedded device or test harness that ingests .3gp, or a low-bandwidth workflow built around the format. For everyday use, MP4 is smaller at equal quality, plays on essentially every current device, and keeps far more of what an MKV holds, so MKV to MP4 is the better choice. 3GP is a compatibility target, not a quality or general-purpose one.

What happens to my MKV's subtitles, chapters, and extra audio tracks?

They are not carried into the 3GP. MKV is a flexible container that can store several audio languages, soft (selectable) subtitle tracks, and chapter markers; the 3GP container holds a single video stream and a single audio stream and has no equivalent for the rest. The conversion keeps one video and one audio track and drops everything else, so if you rely on those, burn the subtitles into the picture beforehand or keep an MKV or MP4 copy alongside the 3GP.

Will the 3GP look worse than my original MKV?

Usually yes, and that is inherent to the format rather than a flaw in the conversion. 3GP is built for low-bandwidth mobile delivery, so it uses small resolutions and low bitrates, and re-encoding into it discards detail to hit that tiny size. You can soften the loss by keeping the resolution no smaller than the target device needs and leaving the Video Codec on H.264, but you cannot make a 3GP match a full-resolution MKV.

Which video and audio codecs does the 3GP output use?

By default this converter writes H.264 video with AMR audio inside the 3GP container, which suits most handsets from roughly 2009 onward. For older phones you can switch the Video Codec to H.263 or MPEG-4 and keep audio on AMR Narrow Band; if the target device supports it, you can also choose AAC audio. The 3GP container itself is structurally based on the ISO base media file format (ISO/IEC 14496-12, MPEG-4 Part 12), the same base layer MP4 uses, which is why it accommodates all of these codecs.

What resolution should I pick for an old phone?

Match the handset. The two safe legacy sizes are 176x144 (QCIF) and 320x240 (QVGA); many early feature phones only decode H.263 at QCIF. Use Preset Resolutions or Width x Height in Advanced Options to set it. Going larger risks a file the phone can't open, while going smaller than the screen needs throws away quality for no benefit.

What is the difference between .3gp and .3g2?

Both share the same MPEG-4 Part 12 base structure, but .3gp is the 3GPP container for GSM/UMTS phones while .3g2 is the 3GPP2 container for CDMA2000 phones (older Verizon and Sprint handsets in the US). This page outputs .3gp. If your target device specifically needs the CDMA variant, it expects .3g2 instead. In our testing, a one-minute 1080p MKV re-encoded to 176x144 H.263 3GP comes out around a few hundred kilobytes — small enough for MMS but visibly soft, which is exactly the format's design point.

How are my files handled after conversion?

Files are uploaded over an encrypted connection and processed on our servers — no sign-up and no watermark. They are deleted automatically a few hours after conversion and are never shared or made public.