Does WebM support transparency?

Yes-VP9 with alpha keeps transparency. FitToMB preserves it when exporting WebM.

Is AV1 playback widely supported?

Most modern browsers and hardware decode AV1, but older devices may fall back to VP9/H.264. Provide MP4 as a fallback when sharing widely.

Compress WebM Online

Q: When should I use WebM vs MP4?

WebM is ideal for browsers, Discord, and alpha overlays. MP4 remains the safest option for email and older devices.

Perfect for creators, screen recordings, and browser-friendly assets. FitToMB hits exact MB targets while keeping VP9/AV1 sharp.

Quick links: 10MB, 25MB, 50MB, plus the Discord guide for server uploads.

Pick your WebM workflow

WebM excels for web delivery and Discord sharing-especially with VP9 or AV1. Choose the workflow that fits your project and let FitToMB hit the exact size.

Target MB mode

Lock to an exact file size-ideal for email, LMS uploads, or Discord limits.

Presets: 10MB, 25MB, 50MB, 100MB.
Two-pass encoding to nail the target.
Preview bitrate before you compress.

Quality (CRF) mode

Let quality float while WebM picks the bitrate. Great when you care about visuals more than an exact number.

CRF suggestions: VP9 (28-32), AV1 (20-26).
Optionally set a max bitrate for safety.
Perfect for long screen recordings.

Resolution toggles

One click to swap between 1080p, 720p, and 480p-ideal when a server forces a tight limit.

Auto scales bitrate with resolution.
Shows expected size before encoding.
Use 480p for 10MB Discord uploads.

Working from your phone? The iPhone compression guide covers capture settings before you convert to WebM. For quick size checks, keep the bitrate calculator open in another tab.

Need exact-size presets? Jump to the 25MB, 50MB, or 100MB playbooks when uploads have strict caps.

Switching containers? The MKV workflow explains when to stay in MKV versus exporting to MP4/HEVC.

Planning long recordings? Use the bitrate calculator to decide bitrate before you capture.

Suggested WebM settings

Use these ranges as a starting point-adjust CRF up for more detail, down for smaller sizes.

Goal	Resolution	VP9 CRF	AV1 CRF	Expected size
Discord 10MB	720p @ 30 fps	32	26	~8-10MB
Email 25MB	1080p @ 30 fps	29	23	~23-25MB
Portfolio 50MB	1080p @ 24 fps	27	21	~45-50MB
Knowledge base 100MB	1440p @ 30 fps	25	19	~90-100MB

Need to meet strict upload rules? See the Discord video size guide for server limits.

FAQ

When should I use WebM vs MP4?

WebM (VP9/AV1) shines for Discord, browsers, and lightweight embeds. MP4 is still best for email and legacy devices. FitToMB lets you export either if you need broader compatibility.

Does WebM support alpha transparency?

Yes-WebM with VP9 can keep an alpha channel. FitToMB preserves transparency when you choose the WebM output option.

What about AV1 playback?

Most modern browsers and devices now decode AV1, but older hardware may fall back to VP9/H.264. If you're unsure, export AV1 for your site and MP4 for legacy platforms.