Compress a Video to 25MB
Fit Gmail's attachment limit — with honest math about the 25MB that's really 18MB.
Runs entirely in your browser. Your videos never leave this device.
25MB is Gmail's famous attachment ceiling; Outlook.com is stricter at 20MB, and most webmail sits somewhere in that range. The catch: email encodes attachments in base64, which inflates them by roughly a third in transit, so a 25MB limit really fits about an 18MB file. This tool compresses your video to whatever exact size you pick, entirely in your browser, with nothing uploaded.
How do I compress a video to under 25MB?
Drop the video into the compressor, set the target size, and download the MP4 — it all runs in your browser, nothing is uploaded. The encoder computes the exact bitrate from the video's duration and automatically retries at a lower rate if the first pass overshoots. If the file is going out as a Gmail attachment, target 18MB rather than 25MB so it survives email encoding.
The facts that matter
| Who caps at ~25MB today | Gmail (25MB, counted as total message size), Outlook.com (20MB); Discord's free tier used 25MB from 2023 to 2024 |
|---|---|
| The encoding catch | Base64 inflates attachments ~33% in transit — target ≈18MB for Gmail, ≈15MB for Outlook.com |
| 1–2 minutes at 25MB | ≈1.7–3.3 Mbps — good 720p; one minute is passable at 1080p |
| 5 minutes at 25MB | ≈670 kbps — decent 480p |
| 10 minutes at 25MB | ≈330 kbps — rough; trim, or share a link instead |
| Output | MP4 (H.264 + AAC), aspect ratio and frame rate preserved |
Get a better result
- Emailing through Gmail? Target 18MB, not 25MB — base64 encoding adds about a third in transit.
- Trim the video before compressing; a fixed size budget stretches much further over fewer seconds.
- Sending to Outlook.com? Its cap is 20MB — target about 15MB to clear encoding overhead.
- For a 10+ minute video, consider a cloud link instead — 25MB spread that thin looks rough.
Frequently asked questions
Why did Gmail reject my 24MB video?
Because Gmail's 25MB limit counts the encoded message, not the file on your disk. Email attachments travel base64-encoded, which adds roughly 33%, so a 24MB file becomes about 32MB in transit. Compress to 18MB or less and it goes through.
Can I set an exact target like 18MB?
Yes — the target size is a free choice, not a fixed preset, so you can enter 18MB (or any other number) and the encoder computes the bitrate for exactly that. That's the right move for Gmail; for Outlook.com, aim for about 15MB.
What quality does 25MB buy?
A one-to-two-minute video gets 1.7–3.3 Mbps, which looks good at 720p. Five minutes lands near 670 kbps — respectable 480p. Past ten minutes there's under 350 kbps to go around and the picture turns rough; at that length a link to cloud storage usually serves the recipient better.
What happens if the output comes out over the target?
The tool aims below the target with a margin, then verifies the finished file's actual size. If it overshot, it automatically re-encodes at a lower bitrate — you don't have to run it twice yourself.
Is the video uploaded to your servers?
No — compression happens inside your browser via FFmpeg compiled to WebAssembly, so the file never leaves your device. That also means no size cap on input files and no waiting on upload bandwidth; the trade-off is that encoding runs at browser speed, so long videos take longer than a desktop app would.
Does it change my video's format or dimensions oddly?
The output is a standard MP4 with H.264 video and AAC audio, which every mail client and phone can play. The aspect ratio is always preserved and the source frame rate is kept — only the bitrate (and with it, fine detail) changes to hit your size.