Where the 25 MB limit comes from
- Gmail and Yahoo Mail: 25 MB per message — but attachments grow by a third, so for email use 18 MB
- Many upload forms, LMS assignments (Canvas, Moodle) and CMS media libraries
- Older Discord limits and some chat apps
How it works
The size of a video is its bitrate multiplied by its length. CompressLab subtracts the sound and the container overhead from 25 MB, spreads the rest over the length and checks the real size after encoding. The result lands just under 25 MB — never over.
The resolution stays as in the original by default. If the video is long and the picture gets blocky, switch Resolution to “Auto” — a smaller frame at the same size looks cleaner.
What fits in 25 MB
At 1080p good quality needs about 4–5 Mbit/s, at 720p about 2–2.5 Mbit/s. So 25 MB holds roughly 0.7 min of 1080p or 1.4 min of 720p at good quality; longer videos still fit, at lower quality — or split them into parts.
Questions
Why is the result slightly under 25 MB?
A small margin keeps it under the limit even when a site counts megabytes differently (1000 vs 1024).
Can I choose another size?
Yes — move the slider or type any size.
Is there a limit on the original file size?
No. Everything runs on your computer, so even very large files work.
Last updated: 2026-10-30