How to compress a video for WhatsApp, email and the web
The size limits on each platform, what resolution and bitrate do, and settings that get a clip under the limit.
A minute of video from a current phone is 150 to 400 MB. That is too large for email, over the limit for most messaging apps, and far more than any social platform will keep after recompressing. Shrinking a video is about deciding how much of that data actually reaches the viewer's eyes, which is much less than the phone recorded.
What determines video size
- Resolution is the pixel dimensions of each frame. 4K is 3,840 × 2,160; 1080p is 1,920 × 1,080; 720p is 1,280 × 720. Halving the resolution quarters the number of pixels, and roughly quarters the size.
- Bitrate is how much data the encoder spends per second, in megabits per second (Mbps). Phones record 4K at 50 to 100 Mbps. Netflix streams 4K at around 15 Mbps and 1080p at about 5 Mbps. There is a lot of headroom.
- Frame rate is frames per second. 30 fps is standard; 60 fps doubles the data for smoother motion, which only matters for sport and gaming footage.
- Codec is the compression method. H.264 plays everywhere. H.265 (HEVC) is about 40% smaller but does not play on many Windows machines and older Android phones without extra software. AV1 is smaller still but support is still uneven.
Platform limits
| Destination | Limit | What it does to your video |
|---|---|---|
| Sends up to 2 GB as a document; as a video, recompresses heavily to ~16 MB | Compress to 720p yourself for a better result than its automatic compression | |
| iMessage | ~100 MB comfortable; larger sends fail or go via iCloud link | Compresses when "low quality mode" is on |
| Gmail / Outlook | 25 MB / 20 MB attachment | Rejects; suggests a cloud link instead |
| Instagram Reels | Up to 4 GB, 90 seconds to 3 minutes | Recompressed to ~1080p at 3 to 5 Mbps |
| TikTok | Up to 4 GB / 10 minutes | Recompressed to 1080p |
| YouTube | Up to 256 GB | Recompressed at every resolution; upload high quality |
| Website (self-hosted) | Your hosting limits | Keep under 10 to 20 MB per clip for reasonable load times |
| Slack / Teams | 1 GB / 250 MB | Rarely a limit; compress for viewers' bandwidth |
Settings that work
| Goal | Resolution | Quality | Size per minute (approx.) |
|---|---|---|---|
| Under 25 MB for email | 720p | Medium to low | 8 to 15 MB |
| WhatsApp with better quality than its own compression | 720p | Medium | 12 to 20 MB |
| Website background loop | 1080p, audio removed | Medium | 20 to 35 MB |
| Social upload | 1080p | High | 40 to 70 MB |
| Keep a copy that still looks great | Original | High | 40 to 60% of the original |
If the result is still too big, the biggest lever is resolution, then quality, then trimming the clip. Removing audio saves only 1 to 2 MB per minute.
Why 720p is usually enough for messaging
A phone screen showing a video in a chat bubble is displaying it at a few hundred pixels wide. 720p already contains more detail than can be seen there. Because the messaging app will recompress anything you send anyway, giving it a clean, sensibly sized 720p file produces a better final result than handing it a 4K file to mangle.
Doing it without uploading the video
The video compressor on this site runs an FFmpeg encoder inside your browser. The engine downloads once, then the video is decoded, scaled and re-encoded on your device as H.264 MP4. Family footage, work recordings and anything else private never leave your computer or phone. It is slower than a desktop app, roughly one to three times the clip's duration on a laptop, but for clips of a few minutes that is a small price for keeping the footage private.