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
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 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.
What can I upload to Resize MKV?
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MP4, MOV, MKV, WebM, AVI, WMV, FLV, 3GP, M4V, MPEG and MPG. The container and codec are probed before anything runs, so a mixed batch is handled correctly per file rather than assumed to be uniform.
Is there a file size limit on Resize MKV?
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Yes: free accounts process video up to 40 MB per file, by far the most generous cap on the site; ffmpeg with x264, x265 and libvpx does the work, which is the same toolchain behind most desktop video software. Video is the one family where the cap is high enough that upload time, not the limit, is what you will actually notice.
Why would a modern-format site run Resize MKV?
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WEBP.to is built around the modern replacement for both of the old defaults: one format that does lossy, lossless, alpha and animation, and reliably lands smaller than the JPEG or PNG it came from. People arrive here having decided the old defaults are costing them bandwidth, and that decision immediately raises the rest: what size, what quality, what happens to the transparency. Resize MKV is on the same upload and the same account so those questions get answered in one place.
Once Resize MKV has run, what is worth doing next?
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The converter on this site moves images to and from WebP, PNG, JPG and AVIF, which is where you decide whether a smaller file is worth losing the older browsers. Doing it in that order matters: pick the pixels first and the container afterwards, because the container is the cheap decision and the pixels are the expensive one.
Do the sibling sites run something different?
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The engines are identical — same libraries, same workers, same caps. What is different is the opinion attached, and the opinion here rests on a property of the format this site is named after: the same .webp extension can hold a lossy VP8 frame, a lossless one, or an animation, so the sensible processing path is decided per file rather than per extension.
What happens to my file, and is an account required?
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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.
