How do I compress WebM files?

Run "npx optimo video.webm" to compress WebM with lossless optimization. For stronger compression, add --lossy. For size reduction through resizing, add --resize followed by a percentage, dimensions, or target file size.

What is the best way to reduce WebM file size?

The two biggest levers are resizing (reducing dimensions to match display size) and lossy compression. Resizing usually has a larger impact than codec-level compression. Sometimes converting to a more efficient format is the best approach.

Compress WebM files

Compress WebM for web-first delivery. WebM can be smaller than MP4 depending on content and encoding settings.

Last updated: 2026-03-18

To compress WebM files, run npx optimo video.webm. Optimo applies FFmpeg-powered compression by default. For stronger reduction, use --lossy or --resize to shrink dimensions — often the single biggest lever for file size.

Start with optimo

First, run optimo on your video file:

npx optimo video.webm

This is safe: optimo keeps the original if the output isn't smaller.

Two big levers

1) Lossy mode

npx optimo video.webm --lossy

2) Resize (dimensions)

npx optimo video.webm --resize w1280

Practical tips

If you need maximum compatibility (especially on some platforms), keep an MP4 fallback.
Use `--resize` to cap resolution before chasing codec-level wins.
For silent loops, muted WebM can be extremely efficient.

Optimize WebM Resize WebM WebM format guide

Consider converting

Sometimes the best compression is picking a better delivery format.

WebM → MP4 WebM → MOV WebM → MKV WebM → AVI WebM → OGV

Popular conversions

Convert GIF to WebM Convert MP4 to WebM Convert MOV to WebM Convert MKV to WebM Convert AVI to WebM Convert WebM to MP4 Convert WebM to MOV Convert WebM to MKV

Frequently asked questions

How do I compress WebM files?: Run "npx optimo video.webm" to compress WebM with lossless optimization. For stronger compression, add --lossy. For size reduction through resizing, add --resize followed by a percentage, dimensions, or target file size.
What is the best way to reduce WebM file size?: The two biggest levers are resizing (reducing dimensions to match display size) and lossy compression. Resizing usually has a larger impact than codec-level compression. Sometimes converting to a more efficient format is the best approach.