1Upload the MKV videos you want resized — work from the largest original you have rather than from a copy you already shrank once.
2Set the new size: for an image, a width and height in pixels with an optional aspect-ratio lock; for a video, one of the preset sizes from 1920x1080 down to 640x360.
3Start the resize; the picture is scaled to the size you chose.
4Download the resized MKV file.
Resize MKV FAQ
What dimensions should I actually target?
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Match the slot it will live in. A full-width web hero rarely needs more than 1920 pixels wide, a content image 1200, a thumbnail 400, and doubling those numbers covers high-DPI screens. Anything beyond that is bytes nobody sees.
Can I keep the aspect ratio, or force exact dimensions?
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Both. Lock the ratio and one dimension is derived from the other, which is what you want almost always. Unlock it and you get exactly the numbers you typed, at the cost of stretching — useful for a fixed slot, wrong for a photograph.
Does the source format affect the result of a resize?
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It does. MKV imposes no codec restrictions and carries unlimited audio, subtitle and chapter tracks, which is why rips use it and TVs often refuse it. That is what decides whether shrinking the file is purely a question of pixels or also a question of re-encoding.
Is there anything specific to MKV I should watch for?
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Yes — MKV places no restriction on what is inside it, so an edit has to carry every audio, subtitle and chapter track across rather than assuming one of each. Worth checking before you resize a file you will not be able to regenerate.
Can I run Resize MKV on several MKV videos at once?
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Yes. Uploads queue in parallel, which matters more here than anywhere else because video jobs are minutes rather than seconds. Free accounts run one file at a time; a pass lifts that.
Does Resize MKV cost anything?
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No. Resize MKV is free without an account, and the output has no watermark, corner logo or intro card. The upload and the result are deleted automatically about 24 hours after the job, which leaves time to download the result.
Why does a WebM site host Resize MKV?
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WEBM.to is built around the container the open web actually chose — VP9 or AV1 with Opus audio, decoded natively by every modern browser and needing no plugin, licence or player. Video is the case where extra round trips hurt most — the files are large and every upload costs real minutes. Running Resize MKV on the same pipeline as the conversions means one upload covers the whole job instead of one upload per tool.
What should I do with the result once Resize MKV is finished?
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The converter on this site moves video between WebM, MP4, MKV, MOV and the rest, or pulls the soundtrack out entirely, without another upload. Sequencing it that way matters more for video than anywhere else: each re-encode is another generation, so the fewer of them stand between the source and the file you publish, the better it looks.
Is Resize MKV here the same tool the sibling sites run?
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The engines are shared — the same ffmpeg build with x264, x265 and libvpx, the same workers, the same limits. What a WebM site adds is a view on containers and codecs: which combinations play everywhere, which need a re-encode and which can simply be copied across. It also starts from one fact about the format this site is named after: WebM is VP9 or AV1 with Opus audio, which browsers decode natively but which most desktop editors still transcode on import.
Do I need an account, and does anything get kept?
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No account is needed. Uploads and results are kept for about 24 hours, which leaves time to download the result, and are then deleted automatically; nobody reads, lists or indexes them. Several files in one job need a paid plan.
