Compress Video

Reduce video file size by re-encoding at a lower quality — choose high, medium or low. 100% in your browser.

How to use

  1. Upload a video file (MP4 or WebM, up to 100 MB).
  2. Choose the quality level: High keeps most detail, Low produces the smallest file.
  3. Click Compress — the video is re-encoded in your browser. Download the result.

About this tool

This tool compresses a video by re-encoding it with H.264 at a constant rate factor (CRF) you choose. CRF 18 is visually lossless, CRF 28 is a good balance of size and quality, and CRF 35 produces a noticeably smaller file with visible quality loss.

The compression runs entirely in your browser via ffmpeg compiled to WebAssembly. No data leaves your device. Processing time depends on the video length and your hardware — expect roughly real-time speed on a modern laptop.

Re-encoding always involves some quality loss compared to the original. If you only need to remove a segment, use the Trim Video tool instead — it copies the stream without re-encoding.

Frequently asked questions

Does my video leave my browser?

No. All processing is local.

What does CRF mean?

Constant Rate Factor — a quality scale where lower numbers mean higher quality and larger files. CRF 18 is nearly lossless; CRF 35 is aggressive compression.

How long does it take?

Roughly real-time: a 30-second video takes about 30 seconds. Longer on older devices.

Can I compress a 4K video?

Technically yes, but the processing will be very slow in the browser. Consider trimming first or using a lower resolution.

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