Common size limits
| Gmail | 25 MB per email |
| Outlook.com | 20 MB |
| Discord without Nitro | 10 MB |
WhatsApp and Telegram also compress videos when you send them normally, which lowers the quality; making the file smaller yourself gives you control over how.
Compress to a size
- Open Compress Video, or the ready-made pages for email and for Discord.
- Choose Target size and type the limit in MB, a little under the real limit to be safe.
- Drop in the video, click Compress and download the MP4.
The video is compressed on your own device, so it takes a while for long videos but nothing is uploaded.
What makes the biggest difference
- Length: the file size grows with every second. Cutting the parts you do not need with Trim Video helps more than anything else.
- Resolution: a 4K phone video at 720p is about a ninth of the pixels and still looks good on a phone.
- Quality setting: Medium removes detail you rarely notice; Strong is for when the size matters more than the look.
When a link is better
A long video will not fit in 10 or 25 MB without looking poor. Upload it to a cloud drive and share the link instead.
Working out the bitrate
A file's size is its bitrate times its length, so a size limit sets the bitrate. Total kbps = size in MB × 8000 ÷ seconds.
- A 2-minute video into 25 MB: 25 × 8000 ÷ 120 = 1,667 kbps. Take off 128 for the sound and about 1,540 kbps is left for the picture, which looks good at 720p.
- The same video into 10 MB: 10 × 8000 ÷ 120 = 667 kbps, or about 570 for the picture after 96 for the sound. That suits 480p.
As a rough guide for H.264, 720p looks good at 1.5 to 3 Mbps and 1080p at 4 to 8 Mbps. Fast motion and grain need more.
Common problems
- The file came out just over the limit. The MP4 container and the sound add a little to the size. Aim about 5% under the limit.
- The video will not play on a Windows PC. iPhones record in HEVC (H.265), which some computers cannot play without an extra codec. Re-encode it as H.264 MP4, which plays everywhere.
- The video is now sideways. Phones often record sideways and mark how to rotate it. If a player ignores the mark, rotate the video itself before compressing.
- It looks blocky in dark scenes. Dark, flat areas show compression first. A slightly higher bitrate or a lower resolution helps more than a stronger setting.