The "math" I used for that is the one taught by personal experience, i.e. I've encoded thousands of files in quite a few formats over the years...hence knowing the ogg files end up smaller than mp3 ones at the same bitrate.
Ogg uses variable bitrate, so even if you set it to encode at 128kbs it's not going to stick to that for a quiet part of an encoding when it doesn't need to. I'm not sure if that is why the files end up smaller, and quite frankly I really don't give a hoot. Kindly RTFM next time, and take more notice in your English lessons: than!=then.

Are you a woman ... That's feminine logic if I ever saw any. "Feminine" does not translate to wrong, and I'm not familiar enough with .ogg files to evaluate the statement. OTOH, disturbed1's logic seems to me to be pretty solid. Granted variable bit rate files are smaller than comparable constant bit rate ones. The solution to that argument would be to compare a vbr .mpg with a vbr .ogg

I favor the idea of telling people to RTFM, but I think in this case you need a mirror.

We know have a few answers and a few irrelevant posts and, to be honest, I can see this thread turning into a flame fest. Remember guys: sometimes someone will genuinely want a proprietary format. Because that's what they want.

Anyway, multios, condolences on your loss. I hope that if you need to send music files again, that you'll find this thread useful.