A useful fact is that a change of saddle height by a certain amount - 1mm reduction for example, will make a change of half that amount - so 0.5mm at the 12th fret. The thicker the string the more room it need to vibrate and so the low E is positioned a little further away from the fretboard compared to high E - the difference is only about 0.5mm at 12 fret which is brought about by a slight change of 1mm to 1.5mm in saddle height from a perfect circle profile - usually saddles can be seen to be a little lower at the high E side.
