Compress MP4 Online

Reduce MP4 file size for sharing, email, social media and web publishing. LessMB compresses MP4 videos locally in your browser so your clips stay private.

Files stay on your device
How it works

Compress MP4 Online for private browser workflows

Compress MP4 in your browser

Select an MP4 file, choose your quality settings, and let LessMB create a smaller version. Processing happens locally using browser workers — no server upload needed.

Control resolution and bitrate

Lowering resolution from 4K to 1080p or 720p often gives the largest file size savings. You can also adjust bitrate and CRF for fine-grained control.

Fast sharing-ready output

The compressed MP4 works across phones, email clients, messaging apps and social platforms. Download the result and share immediately.

Common use cases

Shrink MP4 files to fit strict email attachment limits before sending.

Email attachments

Reduce video size for Instagram, Facebook, LinkedIn and other platforms with upload limits.

Social media

Compress screen recordings and clips for Discord, WhatsApp, Slack and Telegram.

Messaging apps

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If an iPhone video is too large for email, chat, forms or shared drives, you can reduce its file size directly in Safari. LessMB runs video compression in the browser, so the clip stays on your device during the session.

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Google Drive stores your uploaded video file, but preview playback may use processed versions. If your goal is a smaller file for upload or sharing, compress the video before sending it to Drive.

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FAQ

Compress MP4 Online FAQ

Answers for the most common questions about this tool, supported workflows, and local browser processing.

No uploadFree toolBrowser-based
Can I compress MP4 files for free?

Yes. LessMB compresses MP4 files for free in your browser without requiring an account.

How much can I reduce MP4 file size?

It depends on the source. Lowering resolution from 4K to 1080p or 720p can reduce file size by 50% or more in many cases.

Will compressing MP4 reduce quality?

Some quality loss is expected with lossy compression. LessMB lets you preview the result and adjust settings before downloading.