Video Compressor — free online tool
Is your video too big for email, a messaging app or an upload form? Vidlora's compressor re-encodes it using a constant-quality setting to produce a much lighter MP4 file. There is no account to create, no watermark is added, and your file is deleted after you download the result.
Drop a MP4, MOV, WEBM, MKV, AVI file here, or click to choose one
Procesado temporalmente y eliminado despuésDrop a MP4, MOV, WEBM, MKV, AVI file here, or click to choose one
MP4, MOV, WEBM, MKV, AVI
Cómo funciona
What actually happens during compression
Unlike simply changing a file extension, compression means decoding and then re-encoding every frame. The tool relies on FFmpeg and a CRF (Constant Rate Factor) setting: instead of targeting a fixed bitrate, the encoder spends bits where the image is complex and saves them on calm areas. The result is an MP4 whose size depends on the content: a static shot compresses far better than a sports scene full of motion.
Using the tool step by step
Drop your file into the upload area, choose the compression level offered, then start processing. A progress bar shows how far along it is; the wait depends mainly on the video's length and resolution. When it finishes, a download button appears. Then compare the size before and after: if the result looks too degraded, simply run it again with a gentler setting from your original file, never from the version that was already compressed.
When to compress
Typical situations: a smartphone video of several hundred megabytes to attach to an email, a tutorial screen recording to upload to a course platform with limited space, a clip to send in a messaging app, or a video proof to provide to an insurer. Shooting in 4K or at 60 frames per second produces huge files that most recipients will never watch at that quality. Compressing once, at the last moment, avoids piling up quality losses.
Choosing the right quality level
With CRF, a lower value means better quality and a larger file; a higher value gives a smaller file but more artifacts, especially in flat color areas and gradients. For H.264, values around 23 are considered a good compromise and values around 28 a strong compression. The encoding preset affects speed: a slow preset compresses better at equal quality, but takes longer.
Formats and compatibility
The output file is an MP4, the most widely supported container: browsers, iPhone, Android, smart TVs, Windows and macOS. The input can be MP4, MOV, WebM, MKV or AVI, whatever the original codec. The MP4 produced uses a very common video codec, so it plays without any special software. Note that compression does not change the duration or, unless stated otherwise, the image dimensions: to reduce the resolution too, use the video resizer.
Common mistakes and tips
Do not recompress the same file several times: each pass adds defects. A video that is already heavily compressed, such as a social network export, will barely shrink and may even grow slightly. If the gain is small, the real fix is often to lower the resolution or trim unneeded sections with the video trimmer before compressing. Finally, a damaged or protected file may fail: in that case, try converting it to MP4 first.
Limitaciones
Compression is lossy: you cannot recover the original quality from the result. The savings depend heavily on the content, and a file that is already well compressed shrinks very little. Only MP4, MOV, WebM, MKV and AVI formats are accepted, and very large uploads may be refused to keep processing reliable.
Preguntas frecuentes
Will I lose quality?
Yes, a little: video compression is always lossy. With a moderate setting, the difference is often invisible on a phone screen. If you notice blocks or blur, run the process again from the original with a gentler compression level.
How much smaller will my file be?
It is impossible to say in advance, because it depends on the content. A raw smartphone video can lose a large share of its size, while an already optimized export will gain little. Simply compare the sizes before and after.
Is my file stored on your servers?
No. The file is uploaded to be processed with FFmpeg, then deleted after you download the result. We do not store it long term, and there is no sign-up and no watermark on the resulting video.
Why is my compressed video larger than the original?
This happens when the source was already very heavily compressed, for example a file downloaded from a platform. Re-encoding cannot do any better in that case. Try a more aggressive level or reduce the resolution.
Is the sound kept?
Yes, the audio track is kept and encoded into the final MP4. If you only want the sound, use the audio extraction tool instead, which produces a much lighter MP3 file.
What is the difference from the video resizer?
The compressor acts on encoding quality and therefore on file size; the resizer changes the image dimensions in pixels. For maximum reduction you can combine the two: resize first, then compress.