Convert from
- MP4
- QuickTime (MOV)
- AVI
- Matroska (MKV)
Recommended output
- WebM
- MP4
Compress Video
Re-encode large MP4, MOV and AVI files to efficient WebM or compact H.264 MP4, with bitrate and resolution control.
About this converter
MP4, MOV, AVI and MKV are containers rather than codecs: each wraps a video stream, one or more audio tracks and sometimes subtitles. Two files with the same extension can differ in codec and bitrate, so the extension tells you less about size and compatibility than it seems.
This tool accepts those four inputs and rewrites the video in a more efficient encoding. The picture is decoded and compressed again, which is where the size saving comes from.
How it works
Choose an output format
Pick the format you want the result in before you add anything. Every file in the queue is converted to that one format, so the choice shapes the whole run.
Add your files
Drop files onto the page or use the file picker. Each file is checked against the formats this tool accepts, and anything that does not match is reported by name.
Download the result
When a conversion finishes, download the converted file. Uploads and results are deleted after 2 hours, so keep your own copy.
Formats you can convert
Every file below is accepted as input, and the result is written as WebM and MP4. WebM is the open, efficient target for the web; MP4 is the target for players and editors that expect that container.
- MP4 — the most widely played container, usually H.264 or H.265 with AAC audio
- QuickTime (MOV) — Apple's QuickTime container, the default for iPhone and Mac recordings
- AVI — an older Windows container still emitted by capture cards
- Matroska (MKV) — a flexible Matroska wrapper for many codecs, audio tracks and subtitles
Quality and what changes
Video is re-encoded, so the encoder generates the picture again from decoded frames. Keeping the source resolution and frame rate limits the loss; the rate mode decides how bits are assigned, with CRF targeting consistent quality and bitrate mode capping the data per second. Lowering the resolution or frame rate removes detail but saves far more than either mode alone.
Privacy and limits
Guests can convert files up to 100 megabytes and run 5 conversions per day. A free account raises the limit to 500 megabytes and 25 conversions per day, and paid plans go up to 100 gigabytes.
Files you upload and the results you download are kept only long enough for you to collect them and are deleted after 2 hours. After that window nothing of yours remains on the server.
You do not need an account to convert a file; signing in only raises the size and daily limits.
Questions and answers
Which output should I choose?
WebM is the smaller, open target for the web. Choose MP4 when a device, editor or upload service expects that container, even though it is usually the larger of the two.
Does compressing a video reduce its quality?
Yes, because the video stream is encoded again. Keeping the original resolution and frame rate limits the loss, and CRF rate control keeps quality steady across the clip.
Should I lower the resolution or the bitrate?
Lowering the resolution changes what is displayed and saves the most. A bitrate cap keeps the dimensions but softens detail when the limit is tight. Choose based on whether size or sharpness matters more.
How long are my files kept?
Uploads and results are deleted after 2 hours. Download each result as soon as its conversion finishes; nothing of yours remains on the server after that window.