Outlook and many web forms stop at 20 MB. Set to 19 MB here so the file always fits — or 14 MB if it goes in an Outlook email.
Your files stay on your device. Nothing is uploaded.
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File
Length
Size
Result
Estimates may change after processing.
Compression settings
MB
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Where the 20 MB limit comes from
Outlook.com and Microsoft 365 mail: 20 MB (use 14 MB for the video because attachments grow by a third)
Many job application, school and support forms
Some messenger and forum upload limits
How it works
The size of a video is its bitrate multiplied by its length. CompressLab subtracts the sound and the container overhead from 20 MB, spreads the rest over the length and checks the real size after encoding. The result lands just under 20 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 20 MB
At 1080p good quality needs about 4–5 Mbit/s, at 720p about 2–2.5 Mbit/s. So 20 MB holds roughly 0.6 min of 1080p or 1.2 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 20 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.