The only advice I recall seeing is that you just need to "feel" it out--you and whomever else shares the bathroom just need to take a seat on the toilet and figure out what is a comfortable reach without bumping anything. (Also, if you have a holder that's L-shaped--that is, the TP roll slides onto an 'arm' and it's not one of the holders where the TP roll snaps into place between two arms, you'll want to consider how the TP rolls out. My experience with the former showed that if you don't place the opening in the right direction, one good pull of the TP will whip that roll right off the holder.)

Unless you're a southpaw, it should be hung on the left side of the toilet when you're sitting on it, or on a wall directly across from the toilet, (if easily reachable). As far as the height goes, I just put it when it's easy reach for DH and me, but since his legs are several inches longer than mine, and I'm the one who ALWAYS has to sit, I tend to make it easiest for me, other than him........haha!

Thanks :) My husband suggested the same thing. Of course, he said I need to drop my pants to get the full effect. I think I'll leave that to him!! Christy :)

After have many problems with holders coming out of the wall, or holders being too far/too close to us, we decided to use the self standing toilet paper holders in our new home. Will never go back to the wall mount again!

We put our holder at shoulder height because the dogs always gets at it.

Mine is placed directly in front of the toilet.
The reach is just right.