Convert MKV to 3GP Online
Convert movie and anime MKV clips to 3GP for playback on basic phones. Free, no uploads.
.mkv · up to 100 MB
MKV to basic phone
MKV to 3GP: movies and anime for feature phones
Anime and HD movies to 3GP
Convert clips from your favorite MKV files (anime, movies, documentaries) to 3GP CIF playable on Nokia Series 40 and similar phones.
H.264/H.265 to Baseline
FFmpeg.wasm decodes H.264 High/Main, H.265 HEVC, and VP9 from MKV and re-encodes to the H.264 Baseline understood by basic phones.
No uploads, private
Your video files are converted in your browser without passing through any external server.
Ready to gift via microSD
Clips of 1–5 MB per minute, perfect for copying to a microSD card and gifting to relatives with a basic phone.
How it works
Three steps, no hassle
Upload your MKV file
Drag or select your .mkv: movies, series, anime, documentaries. FFmpeg.wasm decodes H.264, H.265, VP9, and other MKV codecs.
Re-encode to 3GP CIF in the browser
Resolution is reduced to CIF (352×288), re-encoded to H.264 Baseline, and the 3GP container compatible with basic Nokia, Samsung, and Motorola phones is generated.
Download your 3GP clip
Get the small .3gp clip ready to copy onto a microSD card and play on the recipient's basic phone.
FAQ
Got questions?
MKV (Matroska) is a high-capacity container designed to store high-definition video with multiple audio tracks, subtitles, and chapters. It was created by Lasse Kärkkäinen and Steve Lhomme in 2002 and became massively popular for HD movie and anime distribution between 2005 and 2010. Basic phones of that era lack the processing power to decode H.264 Main/High Profile at 720p, and have no video decode hardware capable of it; they only understand 3GP with H.264 Baseline at CIF or QCIF.
Yes, that is one of the most common use cases. Trimming a 2–5 minute clip from an anime episode in MKV (the standard distribution format for anime since 2006 in fansub groups like Dattebayo, Eclipse, or Coalguys) and converting it to 3GP lets you send it via Bluetooth or microSD to a relative with a basic phone. The Japanese audio, or whichever audio track is selected in the MKV, is preserved in the conversion.
MKV subtitles (usually ASS/SSA format for anime or SRT for movies) are not burned into the 3GP video by default in the browser conversion, since rendering ASS subtitles requires an additional video compositing operation. If you need subtitles in the 3GP, you will need to use a desktop tool like HandBrake with the burn-in subtitles option before converting to 3GP.
Yes. FFmpeg.wasm decodes H.265/HEVC (the predominant codec in high-quality MKV since 2014–2015, especially in 10-bit anime release groups like HorribleSubs, Erai-raws, SubsPlease) and re-encodes to H.264 Baseline for the 3GP. The process is computationally intensive; a 5-minute HEVC 1080p clip can take 3–8 minutes to re-encode in a modern desktop browser.
At 128 kbps (minimum bitrate for good visual quality at CIF), one minute of video is approximately 1 MB. At 256 kbps (optimal for CIF), approximately 2 MB. For MMS sending, clips must stay below 500 KB (about 30 seconds at 128 kbps) to respect most carrier MMS size limits. For microSD, the practical limit is the card's capacity.
Technically yes, but it is not recommended to do the full file in the browser due to memory limitations (FFmpeg.wasm loads the entire file into RAM). For long movies, it is more practical to first extract the clip of interest (the first 5 minutes, a specific scene) with a tool like VLC, then convert that short clip to 3GP with this tool.
Convert MKV to 3GP: movies and anime for basic phones, H.264/HEVC to Baseline CIF, Nokia and Samsung
MKV (Matroska Video) is an open-source container format developed by Lasse Kärkkäinen and Steve Lhomme from 2002, publicly released in December 2002. The Matroska project built on the MCF (Multimedia Container Format) and simplified it for practical internet video distribution. MKV became the de facto standard container for HD movie and series distribution from 2005–2006, when the DVD and Blu-ray ripping community adopted MKV as an alternative to AVI for storing H.264 with multiple audio tracks and subtitles in a single file. For anime in particular, MKV has been the universal format since 2006: historic fansub groups such as Dattebayo (Dragon Ball, Naruto), Eclipse (Haruhi, Clannad), and Coalguys (K-On!, Bakemonogatari), and their modern successors HorribleSubs (2010–2021), Erai-raws (2017–present), and SubsPlease (2020–present), distribute exclusively in MKV with H.264 or H.265 at 720p, 1080p, or even 2160p (4K). The 3GP format, by contrast, was designed by the 3rd Generation Partnership Project in 2001 as the standard video format for 3G mobile devices with minimal processing and display capabilities. The gap between an H.265 1080p 10-bit anime MKV (typically 350 MB–1.5 GB per 24-minute episode) and a 3GP playable on a Nokia 6300 (H.264 Baseline QCIF 128 kbps, about 25 MB per 24 minutes) represents a file size reduction of 14 to 60 times.
Converting MKV to 3GP addresses a gift-and-share intergenerational use case that persists in 2026. The typical scenario: a user with internet access has a collection of anime episodes or movies in MKV and wants to share a short clip (an anime opening, a memorable action sequence, the first minutes of a movie) with a family member or friend using a basic phone without internet access or streaming platforms. 3GP is the only way for that clip to be playable on a Nokia Series 40, Samsung SGH, Motorola RAZR, or any phone with a 176×144 to 320×240 pixel screen. This use case is especially prevalent in contexts where the basic phone is not temporary but permanent: elderly people who use a basic Nokia as a second or emergency phone, workers in rural areas who use basic Nokia or Samsung phones for their durability and battery life (up to 2 weeks on some Nokia Series 40 models), or people in countries with limited data plans who prefer to receive video directly on a memory card. The anime conversion use case also carries a nostalgia dimension: users aged 25–40 who grew up watching anime on basic phones and now want to share clips from classic or modern series with that same basic-phone playback experience.
Convertir.ai converts MKV to 3GP in the browser with FFmpeg.wasm without sending files to external servers. For MKV with H.264 Main or High Profile codec, the conversion is relatively fast (1–3 minutes for a 5-minute clip on modern hardware). For MKV with H.265/HEVC — especially high-quality 10-bit versions typical of modern fansub groups like Erai-raws or SubsPlease — the process is more computationally intensive: FFmpeg.wasm runs HEVC decoding and H.264 re-encoding entirely in CPU via WebAssembly, without access to the device GPU, which can result in conversion times of 5–15 minutes for 5-minute clips on mid-range hardware. The final result is a 3GP with H.264 Baseline Profile level 3.0 at CIF resolution (352×288), video bitrate of 128–256 kbps, and AAC-LC mono audio at 12.2 kbps, compatible with the playback profile of most Nokia Series 40, Samsung SGH, and Motorola phones from the 2005–2012 era. The file carries no watermark, requires no registration, and is processed entirely on the user's device, ensuring that MKV content — which frequently includes copyright-protected material used for personal viewing — does not pass through any external infrastructure.