Step 1: Supply your MP4 files using the button above or by haul and lay.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Get your converted MKV files.
MP4 to MKV Conversion FAQ
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Branches on raster/vector, lossy/lossless, alpha-channel,
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What does the MP4 to MKV converter do?
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It transcodes a MP4 video into the MKV container. Resolution, frame rate, and aspect ratio are preserved by default — useful when you need a different format for a target player without quality loss.
Will resolution and frame rate be preserved in the MKV?
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Yes. MP4 → MKV keeps resolution, frame rate, and aspect ratio unchanged by default. To change them, use the Resize or Speed tool on the result.
Is the MP4 to MKV conversion reversible?
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You can convert the MKV back to MP4 on this site. If either format involved is lossy, the round-trip is not bit-perfect even though it is visually or audibly close.
Will the converted MKV be a different size than the MP4?
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Modern codecs compress better, so MKV from a legacy MP4 is typically 30-60% smaller at equivalent quality. Conversions in the opposite direction can grow the file.
Is there a file-size limit when converting MP4 to MKV?
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Anonymous uploads are capped at a generous default; signed-in free accounts get a higher cap, and Pro accounts have no per-file limit. Browser memory is usually the practical constraint long before our server-side limits kick in.
Can I batch-convert several MP4 files to MKV at once?
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Yes. Drop or pick multiple MP4 files in one upload — the converter processes them in parallel and returns a ZIP of the MKV results. There is no need to repeat the upload step per file.
What happens to my MP4 files after the conversion?
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Uploaded files and MKV outputs are auto-deleted after a short retention window. We do not inspect, share, or train on user files. Direct download links are time-limited and tied to your session.
Will my MKV play on phones, tablets, and TVs?
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Yes — MKV uses modern codecs that play natively on iOS, Android, Smart TVs, game consoles, and every modern browser.
Do I need to install software to convert MP4 to MKV?
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No. The converter runs entirely in your browser plus our cloud — no plugin, no install, no admin rights. It works on Windows, macOS, Linux, ChromeOS, iOS, and Android.
Do I need an account to convert MP4 to MKV?
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No. MP4 to MKV conversion is free and works without an account. Signing in unlocks higher file-size caps, batch history, and API access.
Is there an API for MP4 to MKV conversion?
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Yes. Every conversion this site offers is also exposed via a JSON API — see /api/ for endpoints, authentication, and rate limits. MP4 to MKV is one of the supported pairs.
What if my MP4 fails to convert to MKV?
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Failures are usually caused by corrupted source files or unsupported MP4 variants. Re-export from the original app and try again; if it still fails, the contact page forwards the file to support so we can diagnose.