How to Compress a Video for Email
Most email providers cap attachments around 25MB. Here's how video compression actually works, and how to shrink a clip to fit without turning it to mush.
Published July 28, 2026
Why your video is too big to email
A phone-shot video at 1080p or 4K can easily run 100–300MB per minute of footage, depending on the device and lighting. Email attachment limits haven't kept pace — Gmail has capped attachments at 25MB for years, and most other providers sit at or below that. A 30-second clip from a modern phone can blow past that limit on its own.
How compression actually shrinks a video
Video compression works on three levers at once. The main one is the constant rate factor (CRF) — a quality target the encoder uses to decide how much detail to throw away per frame; a higher CRF means smaller files and softer detail. The second is resolution: fewer pixels means less data to encode, so downscaling a 4K video to 720p cuts file size dramatically before the encoder even gets involved. The third is audio bitrate, which matters less for size but adds up.
nah.tools' video compressor has an "Email-friendly" preset that combines all three: it caps resolution at 1280×720, targets a CRF of 32 (moderately aggressive), and drops audio to 96kbps — tuned specifically to land most clips under 25MB without needing to guess at settings yourself.
Steps
- Open /media/compress-video and drop in your video.
- Pick the "Email-friendly" preset.
- Run the compression and check the resulting file size before attaching it.
When compression alone isn't enough
A long clip or a source file with a very high starting bitrate might still land above 25MB even at the email preset. Two honest options at that point: trim the clip down to just the part that matters before compressing, or, if the visual isn't essential, pull out just the audio — audio files are a fraction of the size of video. For anything that genuinely needs to stay long-form and high-resolution, a shared link is a better fit than an attachment; no amount of compression settings changes that trade-off.
Frequently asked questions
What is the actual attachment size limit for email?
It varies by provider, but 25MB has been Gmail's long-standing cap, and most other major providers sit at or below that. Treat 25MB as the safe upper bound to aim for unless you know your recipient's exact limit.
How does video compression actually shrink the file?
Three levers: a lower constant rate factor target (which controls how aggressively each frame is compressed), a capped resolution so there are fewer pixels to encode, and a lower audio bitrate. The "Email-friendly" preset caps resolution at 1280×720 and drops audio to 96kbps.
Will my video look noticeably worse?
Some quality loss is unavoidable when the goal is a specific target size rather than a specific quality. For talking-head or screen-recording footage the difference is usually minor; for high-motion or highly detailed footage it's more visible.
Is this actually free and private?
Yes. Compression runs through FFmpeg.wasm entirely in your browser. The one-time ~25MB WASM binary downloads from a CDN on first use and is cached afterward — your video itself is never uploaded.