MP4 Compressor — Free, Online, No Upload
MP4 files from phones and screen recorders are often unnecessarily large. This compressor uses CRF (constant rate factor) — the same algorithm professional editors use — to shrink files dramatically while keeping quality high.
Drag & drop your video here, or click to browse
Max file size: ~2 GB (memory permitting)
Why use this MP4 Compressor?
- CRF compression: target quality, not file size — much smarter than fixed-bitrate compression.
- Default CRF 23 is visually identical to the source for typical viewing.
- Drop CRF to 28 for email-friendly attachments under 25 MB.
- No 500 MB cap (VEED) or 250 MB cap (Kapwing) — local compression has no size gate.
How to use it
Drop your MP4 into the compressor
Phone exports, screen recordings, and downloaded videos all work the same way.
Choose target quality (CRF)
CRF 23 = visually lossless, 28 = email/web friendly, 32 = aggressive shrink for chat apps.
Download the smaller MP4
Output stays MP4 (H.264 + AAC) so it plays everywhere.
What to watch out for
| CRF is quality, not size | CRF 23 is visually lossless and CRF 28 is noticeably soft on faces. You choose a quality and the size follows, which is why the result is not a number you can set exactly. |
|---|---|
| Already-compressed files barely shrink | A file that came off a streaming site or a messaging app has been compressed once. Compressing again mostly adds artefacts rather than saving space. |
| Resolution is the bigger lever | Going from 1080p to 720p saves more than any CRF change and usually looks better than a heavily compressed 1080p. |
FAQ
How much smaller will my file get?
Depends on the source. A 1080p phone export typically shrinks 40–70% at CRF 28 with no visible quality loss for casual viewing.
Why is CRF better than picking a target size?
CRF keeps quality consistent across the clip. Fixed-bitrate compression wastes bits on simple scenes and starves complex ones, leading to inconsistent visual quality.
Does this run in my browser?
Yes — the tool uses FFmpeg compiled to WebAssembly. Your file never uploads to a server, never leaves your device, and there is no signup or watermark.