Hi !
I’ve just finished my little project of compilation of gameplay screencasts. It’s now a video of 3m03s, full HD, 60fps. I tried to export in different formats, but this is something I really don’t know anything about. And for this little 3minutes video, I get a 15Go mp4 file. This is so huge ! I have some complete movies on my computer, full HD too, who are less than 8Go. Why is my file this big and how can I reduce without quality loss ?
Thank you for your help 
Why don’t you just use the setting “Youtube” and only change frame rate?
https://support.google.com/youtube/answer/1722171?hl=en
Try using these settings as a baseline…
As mentioned above, start with the YouTube Preset from the Export panel, or the H.264 ones.
Gradually increasing your knowledge about video codecs and how their encoded, will help you even more, long term.
I did it. It’s still 4Go but I guess I can’t do better. Thanks
“better” is relative. Encoding is just a compromise.
You can change the settings to have a lighter file, but you’ll have less quality.
Just dig in the settings and try to change quality rate or size of bitrate.
In Export > Codec tab, reduce the quality % or bitrate depending upon the Rate Control selection.
Regarding quality %, I’m curious: when I’ve exported files that are smaller than the originals and set the quality to 100%, I could swear that the comparison would have made the new files much larger than the originals, were the lengths equalled out. Not a complaint at all, just a question. Does setting quality to 100% increase the filesize in some way? If I were to essentially load a clip and export it with the exact same settings, but at 100%, would it just be lossless, or would it somehow gain information?
Yes, because the quality percent is not relative to the source video quality. It is independent; a new file is created. If you do not apply some compression (100%), it is going to be big. If you apply very much compression (10%), it will be small but ugly. Note, I did not say “bigger” or “smaller.”
No, it will lose a “generation” of quality because it is decoded and then encoded.