How much smaller will my video get?

It depends on the source. Videos recorded at a high bitrate often shrink 40–80% with little visible change at balanced settings. Already-compressed clips save less.

How does target file size mode work?

The tool estimates a video bitrate from the clip length and your target size, then encodes toward it. Container overhead and codec behavior mean the result can land slightly above or below the target.

Does compression reduce quality?

Yes. Lower bitrates and smaller resolutions discard detail. The Balanced preset is a good starting point; High quality keeps more detail at a larger size.

Which formats can I compress?

Inputs can be MP4, MOV, WebM, or MKV when the browser can decode them. Output is MP4 for compatibility or WebM for a smaller file.

Why does a large video fail?

The result is assembled in browser memory. Very large or very long files can exhaust memory, especially on mobile. Keep inputs under about 512 MB and close other tabs.

Free Video Compressor Online — Reduce Video Size

What Video Compressor helps you do

Shrink an MP4 or WebM file by lowering its bitrate, capping the resolution, or aiming at a target size for a specific service. Compression runs on your device, so a private recording or an unreleased demo never has to leave the machine. The presets trade detail for size, and the target-size mode works backwards from the length of the clip to choose a bitrate that can fit the limit you name.

Decoding, compression and muxing happen in your browser. Haivix never receives the file, and there is no server-side copy to delete afterwards.

How it works

The tool decodes the source with WebCodecs and re-encodes it with a lower bitrate or a smaller frame size. In preset mode you choose how aggressively to discard detail; in resolution mode the long edge is capped and the short edge follows the source ratio; in target-size mode the available bitrate is calculated from the duration and the requested size, then the encoder aims at it. Container overhead and the encoder's own decisions mean the final number can land slightly above or below the target.

How to use Video Compressor

Load the source video and read the current size, resolution and duration.
Choose a preset, a resolution cap or a target file size.
Pick MP4 for compatibility or WebM when you want a smaller output.
Start the compression and leave the tab open until it finishes.
Compare the result size with the original and preview the quality.
Download the compressed file, or raise the quality and try again.

When to use it

Fit a screen recording into an email attachment or a chat upload limit.
Reduce the size of a demo that will be embedded on a page.
Prepare a clip for a phone or a slower connection.
Trim the storage cost of archived recordings that do not need full quality.
Test how a video looks at a lower bitrate before publishing it.

When not to use it

Do not compress a file that is already small; re-encoding may add artifacts without saving much.
Avoid a heavy compression pass on a master file you still need to edit.
Do not expect a target size to be met to the kilobyte; the result is an estimate.

Example

A 180 MB screen recording of a product demo needs to fit a 25 MB email limit. Target-size mode on a six-minute clip calculates a video bitrate that leaves room for a small audio track, and the balanced preset keeps interface text readable. The output lands close to the target, and a second pass with a slightly lower target fixes any overshoot.

What you can do with Video Compressor

Compress MP4, MOV, WebM and MKV inputs that the browser can decode.
Cap the resolution without changing the aspect ratio.
Target a size in megabytes instead of guessing a bitrate.
Keep the audio track and re-encode it alongside the video.
Preview the result before downloading it.
Run the whole encode locally, with no upload progress bar to wait for.

Example workflow

Start with a trim so the compressor only processes the section you intend to publish. Fewer frames mean a faster encode and a more predictable target size. After compressing, check the output on the device where it will be viewed, since a phone screen hides artifacts that a desktop monitor exposes.

If the file is still too large, lower the resolution before lowering the quality preset. Downscaling removes more bytes than a mild quality change, and text remains legible at 720p on most screens.

What to know before you start

Compression is lossy; detail is discarded and cannot be restored from the output.
Very large or very long files can exhaust memory, because the result is assembled in the browser.
Target-size mode approximates the container overhead and can miss the exact number.
The available codecs depend on the browser, so the same preset can produce slightly different files.
Audio is re-encoded, which can change the sound of low-bitrate sources.

Common mistakes

Compressing before trimming and spending time on footage that will be cut.
Choosing the smallest preset for a recording full of small text.
Ignoring the resolution cap, then wondering why the file barely shrank.
Deleting the original after a compression pass that has not been reviewed on the target device.

Troubleshooting

If the encode fails near the end, the tab likely ran out of memory. Close other tabs, lower the resolution and try a shorter section. Splitting the file and compressing the parts separately is more reliable than one very large job.

If the output looks soft, raise the quality preset or reduce the resolution less aggressively. Screen recordings with sharp text suffer most from low bitrates, while camera footage tolerates them better.

If the result is larger than the source, the source was already efficiently encoded. In that case, keep the original or convert the container without re-encoding instead of forcing another lossy pass.

Video Compressor