I am wondering what is the standard. I suppose that being flush (no pun intended) could be a standard, but somehow I think that there should be some sort of small but discernible distance.
Code minimum is 15" from the centerline of the bowl to any wall, fixture or appurtenance on either side.
Under the IRC there is a frontal clearance of 21" from the front edge of the bowl to any wall, fixture or appurtenance.
Under the UPC the frontal clearance is 24".
Although those are the code minimums, in the real world those distances are really tight for comfort.
No, I meant the distance from the back of the toilet to the wall - something on the order of 1/2-1".
The standard setback is 12" from the center of the closet flange to the finished wall.
The actual clearance between the back of the tank and the finished wall will vary from one manufacturer to another.
There is no standard or requirement for the gap between the back of the toilet and the wall. Stick with a 12" setback and let the gap be what it will be. If you try for less setback to minimize the gap, you may have a fit problem in the future when you go to install a different toilet and find it varies enough that it hits the wall.
OK, so you all are saying that the center of the toilet drain should be 12" away from the center of the wall? Or 12" from the finished wall?
Finished wall. Too much discrepancy on center of walls, 2x4 studs, 2x6 studs, 2x3 for a mobile home.
If you'd pick up that $19.95 basic plumbing book I suggested (The Black and Decker is a good one with lots of pics) and a copy of Code Check, you'd already have answered most of your many basic technical questions that you seem overloaded with.
The aesthetic questions are mostly a matter of your own personal taste.
DO NOT just assume that you have a 12" offset. You need to measure from the bolts to the wall. As an example I have more rare 14" offset. If I had bought a 12" offset toilet I would have had a 2" gap from the back of the toilet tank to the wall. I have seen any where between 1/2" to an 1 1/2" space. You want atleast enough room to be able to put the tank lid on without scraping paint.
I have a 50 yr old house with a newer 1.6 gallon toilet and a 12" offset. Take the lid off the tank and a paint roller goes behind the toilet quite comfortably. Saves a lot of work and mess when repainting.
"I have seen any where between 1/2" to an 1 1/2" space. You want atleast enough room to be able to put the tank lid on without scraping paint."
Enough room for a compact roller (about 1 inch) is a good idea.