I know what your saying to yourself, "Why arn't these storage space estimations as competent and amazing as me?"
Linux is crazy what can I say?
The others are right though, DISKS shows you your actual space that is left after system reserve. Nautilus shows you the space you have left after that, as well as after all those little kawaii cashies and tempies rolling around there to make your computer navigation faster.
And yes, Stacer does things its own way too, but its so good at doing it, I just love it. HEHE
At the end of the day, if you have the thought in your amazing head, that you don't have enough storage space and you want more, thats when you go get yourself a larger SSD drive. Then you will have increased storage, and then you can be happy!
Hey Rui, one of these nights when the skies are clear, have a look up, you might see a shooting star. hehe