Compress an MP4 video without uploading it
MP4 is already a compressed format, so shrinking it further means re-encoding at a lower bitrate. Instead of guessing a quality setting, you pick the size you need in MB and the tool works out the bitrate from the video's duration. The output is a standard H.264/AAC MP4 with faststart, so it plays anywhere and streams quickly.
Last updated September 2026
Compress an MP4 →How to do it
- Open the compressor.
- Load your MP4.
- Choose a preset (WhatsApp, email, Discord) or set a custom size with the slider (2–500 MB).
- Optionally lower the resolution — this matters most for long videos at small sizes.
- Compress and download the new MP4.
Tips
- If the target is bigger than the original's bitrate allows, the file won't shrink — you can't add quality back.
- Bitrate ≈ target size ÷ duration. Halving the length lets you double the quality at the same size.
- Very long or 4K MP4s are limited by browser memory; trimming first helps on phones.
FAQ
Will compressing an MP4 lose quality?
Some, since it's re-encoded at a lower bitrate. At sensible targets (and with a lower resolution for long clips) the difference is often hard to see on phones and laptops.
Is there a file size limit?
There's no server limit because nothing is uploaded. The practical limit is your device's memory, which is tighter on iPhones.
Why is it slower than desktop apps?
Encoding runs in WebAssembly inside the browser, which is slower than native software with hardware encoders. The trade-off is that your file never leaves your device.