Step 1: Transfer your MKV files using the button above or by slide and deposit.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Retrieve your converted MP4 files.
MKV to MP4 Conversion FAQ
How do I re-encode MKV to MP4 without losing video quality?
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Upload your MKV file and the converter runs a CRF-based re-encode targeting visually-lossless MP4 output (CRF 18 by default, lower values = larger file / higher quality). The codec is chosen to match the MP4 container — H.264 for broad-compat MP4, H.265 for size-efficient MKV, VP9 for WebM, AV1 for newer pipelines. MKV is codec-agnostic: H.264, HEVC, VP9 and AV1 video sit happily beside AAC, FLAC, Opus, DTS or Dolby audio in the same file. Almost every MP4 in the wild is H.264 video with AAC audio; the container also legally holds HEVC, AV1 and VP9.
My MKV has several audio tracks — do they all survive into the MP4?
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Not dependably. MKV stores multiple audio streams as first-class tracks, but MP4 playback support past the first track is inconsistent, so most players will only ever expose one. Choose the track you actually want before converting; the others are better extracted to their own files than left in a container that hides them. MKV is the archival container of choice because it stores unlimited audio tracks, soft subtitles, chapter markers and cover art in one file. MP4 only supports one widely-honoured subtitle format (mov_text), and multi-track audio is unreliable outside desktop players.
Will the MP4 play in a browser when the MKV would not?
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Yes, and that is usually the whole reason for the conversion. An MKV 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.
Both MKV and MP4 are modern containers — which should I actually keep?
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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.
Which video codec does the MP4 output use?
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It depends on the MP4 container. MP4 defaults to H.264 for the broadest playback support across phones, browsers, and Smart TVs. MKV defaults to H.265 / HEVC for roughly half the file size at equivalent quality. WebM defaults to VP9. The advanced options expose explicit codec choice if you need to override. MP4 is ISO/IEC 14496-14, standardised in 2001 and derived from the same QuickTime box layout MOV uses.
Will my audio track survive MKV to MP4 conversion?
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Yes. When MKV and MP4 share an audio codec (e.g. both carry AAC), audio is re-muxed with no re-encode — bit-identical. When the codecs differ, audio is transcoded to AAC / Opus / Vorbis depending on what the MP4 container supports. Multi-track audio (commentary, alternate languages) is preserved.
Can I keep the original framerate when converting MKV to MP4?
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By default yes — a 24fps MKV stays 24fps in MP4; a 60fps MKV stays 60fps. If you need to change rate (e.g. interlaced 29.97 → progressive 30, or 60 → 30 for upload limits), the framerate option handles 3:2 pulldown, deinterlacing, and frame-blending in the same encode pass.
How much will the file size change going from MKV to MP4?
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Same-codec re-mux (MKV H.264 → MP4 H.264 just changing container): nearly identical size. Codec change can swing dramatically: H.264 → H.265 typically halves the file at the same visual quality; VP9 is roughly comparable; AV1 cuts another 20-30% but is slower to encode.
Will the MP4 file play on iPhone, Android, and Smart TVs?
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MP4 / H.264 plays natively on every modern device. MOV / H.264 plays on Apple devices and most TVs but not always on older Android. MKV needs VLC on iOS. WebM is browser-first. The advanced options include a "device compatibility" preset that picks the safest MP4 codec / container for your target.
How long does converting a 1-hour MKV video to MP4 take?
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Same-codec re-mux is near-instant — 30 to 60 seconds for a 1-hour file. A full codec re-encode runs at roughly 0.3-0.7x source duration on our GPU pipeline, so a 1-hour MKV → MP4 finishes in 18-40 minutes depending on resolution and target codec.
What is the maximum resolution supported for MKV to MP4?
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Up to 8K (7680×4320) on Premium plans. Free conversions are capped at 4K (3840×2160) by the per-file size limit. HDR metadata (HDR10, HDR10+, Dolby Vision when present) is carried through where both MKV and MP4 containers support it.
Is my MKV video private during conversion to MP4?
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Yes. Uploaded video files are processed in isolated workers, never viewed by a human, never indexed, and deleted within minutes of completion. The retention window is documented at /privacy/ and we publish no training corpus from user uploads.
