This is how chrome show the width and height of the div :

which is correct, in fact the height is 1466. But, if I do this :
$(document).ready(function () {
console.log($('#container-altezza-fisso').height());
});
it prints 1418. It doesnt have any padding/margin. Why? And how can I fix it?
That’s because on DOMReady some images are not loaded completely. You should call the height on window load.
You can also use
outerHeight: