# Video Compressor - Shrink MP4, MOV, WebM for Email or Upload

Page: https://hirantha.me/tools/video
Part of: Hirantha Sandaruwan Lakshan free tools (https://hirantha.me/tools)
Updated: 2026-07-31

Shrink a video so it's small enough to email or message.

This is a free tool that runs in the browser: open the page to use it. File tools process files on the visitor's own device; files are never uploaded or stored. No account, sign-up, payment or watermark.

Shrink a video so it fits an email attachment limit or uploads faster, entirely in your browser using the same hardware video encoder your operating system already has. No upload, no watermark, no length cap beyond what your device can handle.

The video is decoded and re-encoded using WebCodecs, the browser's native hardware-accelerated codec API - the same kind of API video call apps use - rather than a slow software encoder running in JavaScript.

Output is always MP4 with H.264 video and AAC audio, written with the file's index placed at the front so it starts playing immediately in email clients and messaging apps instead of downloading fully first.

Before starting, the tool checks whether your browser can actually decode the source codec. iPhones have recorded in HEVC (H.265) by default since iOS 11, and many desktop browsers, especially Chrome on Linux, can't decode it - the tool names this directly instead of failing with a generic error.

Compression presets at a glance:
| Preset | Max height | Audio | Use it for |
| --- | --- | --- | --- |
| Email / message | 720p | Stereo, low bitrate | The default - small enough for most attachment limits, still sharp on a phone |
| Balanced | 1080p | Stereo, medium bitrate | Keeping full HD detail while still cutting the file down |
| Smallest | 480p | Mono, very low bitrate | Getting under a hard size cap when quality is secondary |

Q: Is my video uploaded to a server?
A: No. Decoding, compressing, and re-encoding all happen locally using your browser's built-in video codec.

Q: Why does it say my video can't be processed?
A: Usually an HEVC (H.265) video on a browser that lacks a hardware decoder for it - common with iPhone videos on Linux Chrome. Re-exporting the video as H.264 first, or opening it in Safari, usually resolves it.

Q: Is there a file size limit?
A: There's a soft warning on very large files on mobile, since phone browsers can run out of memory, but no hard cap - it depends on your device.

Q: Will the compressed video still play inline in Gmail or WhatsApp?
A: Yes - the output is standard MP4/H.264/AAC with the file index placed at the front specifically so it previews inline rather than requiring a download.

Q: Can I cancel a compression partway through?
A: Yes, cancelling stops the encoder immediately rather than waiting for the current operation to finish.

Q: Does it work on Firefox for Android?
A: Not currently - Firefox for Android doesn't implement WebCodecs, so the tool detects this and explains it rather than silently failing.

Q: How much smaller will my video get?
A: Commonly 60-90% for phone footage, which is usually recorded at a far higher bitrate than it needs. Already-compressed downloads have much less to give.

Q: Does compressing lose quality?
A: Yes, re-encoding is lossy. The presets are chosen so the loss isn't obvious at normal viewing size, but heavy motion and fine detail are where it shows first.

Sources: WebCodecs API - MDN (https://developer.mozilla.org/en-US/docs/Web/API/WebCodecs_API); Advanced Video Coding (H.264) (https://en.wikipedia.org/wiki/Advanced_Video_Coding); High Efficiency Video Coding (HEVC) (https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding)

Related tools:

- [Audio trimmer](https://hirantha.me/tools/audio.md): Cut a section from an audio file and convert it to MP3, M4A, or WAV.
- [Image compressor](https://hirantha.me/tools/image.md): Shrink a photo or convert it between JPG, PNG, and WebP.
- [MOV to MP4 converter](https://hirantha.me/tools/mov-to-mp4.md): Convert an iPhone or camera MOV video to MP4.