Compress a Video in the Browser Before Sharing or Uploading

Introduction

Video files get large quickly. A short screen recording exported from a laptop can be 80 MB, a phone clip can be several hundred megabytes, and a product demo can be too heavy for chat, email, or a CMS field even when the content is only a minute long.

The Video Compressor is built for short, practical compression jobs. It uses ffmpeg.wasm in the browser after you choose a file and start processing. Processing is handled in the browser for this tool based on the current public implementation. Avoid entering sensitive media unless you have reviewed the implementation and your own data handling requirements.

The goal is not to make every video tiny. The goal is to choose a reasonable file size while keeping the parts viewers need to inspect readable.

Real-world scenario

You recorded a 75-second onboarding clip for a help article. The original MP4 is 96 MB. The help center accepts videos under 30 MB, and the clip mostly shows UI panels and cursor movement.

A practical compression pass might be:

• Output format: MP4
• CRF: 30
• Max width: 1280 px
• Audio bitrate: 96 kbps
• Keep duration unchanged

After export, inspect the result. If the UI text is too soft, lower CRF to 27 or keep the original width. If the file is still too large, trim dead time at the start and end before compressing again.

What changes file size

Duration is the biggest lever. Removing 15 seconds from a one-minute clip often helps more than aggressive quality settings.

Resolution matters when the original is larger than the viewing context. A 4K screen recording embedded at 720 px wide is usually wasting bytes.

CRF or quality controls visual detail. Higher CRF usually means smaller files and more visible compression. Lower CRF keeps more detail and makes a larger file.

Audio bitrate matters for videos with speech or music. For a silent UI demo, consider using the Video Mute Tool first.

Common mistakes

Compressing before checking the source. Open the file in Video Info Inspector first. You need duration, dimensions, and estimated bitrate before guessing settings.

Shrinking UI recordings too far. Screen text becomes hard to read before people notice other quality problems. Keep UI demos at a width that preserves text clarity.

Using a phone for large conversion jobs. Browser video processing can use significant CPU and memory. On mobile, start with shorter clips and smaller outputs.

Limits

This tool is better for short clips, screen recordings, and everyday publishing prep than for long professional editing jobs. Large files can fail because of memory, codec support, or browser limits. Unsupported codecs may need a desktop editor or command-line ffmpeg.

If the source is already heavily compressed, a second compression pass can make it look worse without saving much space.

Next steps

• Video Compressor — reduce a video with CRF, width, audio bitrate, and format controls
• Video Info Inspector — check duration, size, dimensions, and estimated bitrate first
• Video Bitrate Calculator — plan a target bitrate from duration and target file size
• Video Trimmer — remove unused intro or outro time before compressing

Final practical note

Use one small test export before committing to a full compression pass. If the sample keeps text readable and motion acceptable, apply the same settings to the whole clip.