Video Converter
Convert MKV, MOV, WebM, or AVI to MP4 and back — right in your browser.
No installs, no upload, 100% free.
Convert a video in three steps
A free video converter that runs entirely in your browser. Drop a file, pick the format, download.
- Step 1
Upload your video
Drag a video into the upload area, or click to browse. MKV, MOV, WebM, AVI, MP4, M4V and more all work — up to 1 GB.
- Step 2
Pick the output format
MP4 for compatibility, WebM for the web, MKV or MOV when a tool demands it. Optionally downscale to 720p/480p for speed and size.
- Step 3
Convert and download
When the codecs fit the new container, the video is repackaged losslessly in seconds. Otherwise it re-encodes on your device — nothing is uploaded either way.
Why videos need converting
Same video, wrong box — most 'unsupported file' errors are just the container.
MKV to MP4
Players, phones, and editors that reject MKV usually accept the exact same video in an MP4 — a lossless repackage, done in seconds.
MOV to MP4
iPhone recordings open everywhere once they're MP4 — usually without re-encoding a single frame.
WebM for the web
Screen recordings and web video land as WebM; convert them for editors — or into WebM for lean embedding.
Lossless when possible
The converter tries a remux first: same video and audio bits, new container, zero quality loss.
Downscale to share
Drop a 4K clip to 720p while converting — smaller, faster, and fine for a chat or a review.
Need the dialogue?
If what you really need is what's said, SlayScribe transcribes the video to text — no conversion required.
Remux first, re-encode only if needed
A video file is a container (MP4, MKV, WebM…) around compressed streams (H.264, VP9, AAC…). When the target container accepts your streams, conversion is just repackaging — instant and lossless, and that covers most MKV/MOV→MP4 jobs. Only when the codecs genuinely don't fit (say, VP9 into MP4 for an old player) does the converter re-encode — in your browser that's slow, roughly the video's duration or more, so the UI warns you and offers 720p/480p to cut the wait.
Frequently asked questions
Is the video converter free?
Yes — the video converter needs no account, adds no watermarks, and sets no conversion limit. Every conversion runs in your browser.
Will I lose quality?
Not when a lossless repackage is possible (most MKV/MOV → MP4 cases). If a re-encode is required, the UI says so — that pass trades some quality for compatibility.
Why is my conversion slow?
The conversion needed a re-encode, and browsers encode video at roughly playback speed. Choosing 720p or 480p speeds it up several-fold; a lossless remux, when possible, takes seconds regardless of size.
Which video formats can it convert?
In: MP4, MKV, MOV, WebM, AVI, M4V and most common containers. Out: MP4 (H.264), WebM (VP8), MKV, MOV.
Is my video sent to a server?
No. The whole conversion happens locally on your device — up to 1 GB per file.
Can I just extract the audio?
Yes — use our Video to MP3 converter, or Video to Audio for M4A/FLAC/WAV output.
Need the words, not just the audio?
SlayScribe turns any audio or video into accurate text in seconds — transcripts, captions, and subtitles in 99 languages.
Transcribe to text