WebM video caps uploads at Web or CMS MP4 upload 100 MB, Email or chat attachment 20 MB, Small form upload 10 MB. VidSmaller compresses any video down to 95 MB so it fits on the first attempt — H.264 MP4 out, no watermark, nothing to install, no account needed to try it. Cloud encoding keeps running if the tab closes. The no-account trial accepts videos up to 3 minutes and 200 MB; paid plans accept files up to 1.5 GB.
WebM is designed for the web and commonly carries VP8, VP9 or AV1 video. It can be efficient already, but upload forms and editing software often require MP4 instead.
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Checking your file limits…
Supported: mp4, webm, mov, mkv, avi, wmv and 33 formats in all
Choose a target for the destination, then export H.264 MP4 when compatibility matters more than retaining the WebM container.
| Plan / upload method | Maximum file size |
|---|---|
| Web or CMS MP4 upload | 100 MB |
| Email or chat attachment | 20 MB |
| Small form upload | 10 MB |
Limits verified 2026-10-31. Sources: MDN — Media container formats: WebM · WebM Project — About WebM
Every other page tells you the limit and stops there. The limit is the easy half. Here is the half that decides whether your video is watchable: at a 95 MB target, this is exactly how much bitrate is left for each duration, and the largest resolution that bitrate can carry without falling apart.
| Video length | Bitrate left for video | Resolution it carries | Verdict |
|---|---|---|---|
| 1 min | 12,888 kbps | 1440p | Looks fine |
| 5 min | 2,475 kbps | 720p | Looks fine |
| 10 min | 1,174 kbps | 480p | Looks fine |
| 30 min | 306 kbps | 360p | Visibly rough |
Method: the bitrate column is arithmetic — 95 MB spread across the duration, minus 128 kbps for stereo audio and 2% for container overhead. It is a hard ceiling, not an estimate. The resolution and verdict columns are a recommendation, derived from published H.264 bitrate ladders and pulled down about a third, because re-encoding footage that has already been compressed once survives lower bitrates than encoding a clean master does. Deliberately conservative — we would rather under-promise than tell you a video will look fine when it will not.
The left column is what you have to spend at each length; the cells are what each resolution needs. Green means you clear it comfortably, amber means it is watchable but soft, and grey means pick a smaller frame. Reading down a column shows how long a clip can get before that resolution stops being worthwhile on WebM video.
Source: Computed, not measured — no encoder was run to produce this figure · Method: 95 MB spread over the duration, minus 128 kbps audio and 2% container overhead. Thresholds come from published H.264 bitrate ladders, reduced by about a third for re-encoded source.
WebM commonly carries VP8, VP9 or AV1. VP9 and AV1 can outperform H.264 at the same visual quality, so converting solely to chase a smaller number may be counterproductive. Keep the source when the website, browser or platform supports its codec. Convert when a form, editor, messaging app or recipient requires MP4 compatibility.
Some WebM files use alpha transparency or audio choices that do not map directly to a basic H.264 MP4 delivery file. A normal MP4 export can flatten transparency and keep only a primary audio track. Preview the full output when the source is an animation, overlay or asset intended for compositing rather than ordinary playback.
A small website animation may not need the source resolution, while a screen recording with text can become unreadable if scaled down too far. Set the target from the upload rule, then inspect edges and text at the display size users will see. If compatibility is the only problem and size is already acceptable, avoid an unnecessarily aggressive target.
MP4, MOV, MKV, AVI, WebM and 33 formats in all. Nothing to install — your browser uploads over a one-time link and the file never touches a third party.
We pre-set it below the hard ceiling on purpose. A target-size encode usually lands within a couple of percent of the number you gave it, but we have measured footage that overshoots by up to a tenth — and landing over a hard limit means the upload fails. Change it if you want a different number.
Encoding runs on our servers, so you can close the tab. The result comes back with no watermark on any plan, in an MP4 that a WebM video will accept.
Yes. The video is decoded and encoded as H.264 in an MP4 container so it works in more forms, editors and devices.
The container does not set file size. Long duration, high resolution, high frame rate or a generous source bitrate can still produce a large WebM.
It can at equal visual quality because newer codecs are often more efficient. Use the target size when compatibility is the binding constraint.
Keep it when your playback stack supports the source codec. Export MP4 when a destination rejects WebM or broad device playback is more important.