Compress video to 20 MB

Who enforces 20 MB, and since when

Discord is the reason this number suddenly matters. Free accounts were capped at 10 MB per file from late 2024 until mid-August 2026, when Discord doubled it to 20 MB for everyone without Nitro — reported on 13 August 2026 by Dexerto. Nitro Basic stays at 50 MB and Nitro at 500 MB.

The other 20 MB is much older and catches people out at work: classic Outlook for Windows has refused attachments over 20 MB (20,480 KB) by default on POP3, IMAP and HTTP accounts since Outlook 2013, and shows “The file you’re attaching is bigger than the server allows” when you cross it. An Exchange mailbox is governed by a separate server-side limit, which Microsoft documents as 10 MB by default (Microsoft Learn, KB 2813269, checked 6 September 2026).

So a 20 MB target is not an arbitrary round number — it is the exact ceiling on the most common free Discord upload and on the default desktop Outlook attachment.

How the 20 MB target is hit

The tool reads your clip’s duration and works backwards: 20 MB spread over a 30-second clip is a generous bitrate, and the same 20 MB over ten minutes is not. It sets the video bitrate to aim just under the target, keeps roughly a 4% margin for container overhead, and downscales the resolution only when the arithmetic makes that unavoidable.

One honest limit of that method: it aims, it does not clamp. When you ask for only a small reduction — a 21 MB clip down to 20 MB — the encoder has almost no room to work with and the result can land several percent over — measured on this tool, an 11.0 MB clip asked down to the 8 MB target came out at 8.5 MB, about 7% above the line. If the file has to be under the line, pick the target one step below the one you actually need, or trim a few seconds off; both give the encoder the headroom it needs to land where you asked.

That is why length matters more than anything else you can change. Trimming a four-minute recording to the forty seconds you meant to send multiplies the bitrate budget by six at the same file size — the single biggest quality win available here. Use the trim control above, or the dedicated video cutter.

If 20 MB is not your number, the neighbours are one click away: 10 MB for the old Discord cap and for forums, 25 MB for Gmail attachments, and 8 MB for anywhere that still quotes the classic limit.

Nothing is uploaded to make it smaller

An upload limit is a strange thing to solve by uploading, which is what most “compress to 20 MB” services ask you to do — your file goes to their servers, waits in a queue, and comes back. Here the encode happens in this page with WebAssembly, so there is no queue, no daily cap and no service-side size ceiling; the practical limit is your own browser’s memory.

The output is a standard H.264 + AAC MP4 with the moov atom written at the front, which is what lets it start playing straight away when Discord or a mail client previews it. If the destination cares about the format rather than the size, the MOV to MP4 and WebM to MP4 converters do that job in the same pass.