Where should a toilet supply be?

How far left or right of center should a copper stub for a toilet supply line be from the center of the drain?

There are recommended distances for all of the Toto models and probably other brands as well, but the main thing is not to be to close to the center. With the flex supply lines that are mostly used now, distances more or less than the recommend won't make that much difference. Heck, mine comes through the floor! I suppose if one is installing new plumbing and has a toilet selected, it would be reasonable to use the distance recommended for that toilet, but replacing a toilet with another, you would just use the existing supply.

Depends on the toilet. If I remember correctly it was 8 inches left of center (as facing the wall) for my Toto Carlyle. Other toilets may be closer so it is best to check the rough-in dimensions drawing for the toilet you are installing.

Or just make it 10 inches and you will be sure to fit.

I just moved two toilet supplies to make them compatable with the Toto's I plan to install. I think the std was about 4 or 5 inches to the left. The skirted Toto's need them further to the left so I moved them over a few more inches. Left side facing the toilet is the std location.....

8" to the left of center works for just about anything.

supply

I put mine 6" to the left and 8" up, but you really want to check the toilet. For example, Kohler once made a toilet which had the supply on the right so the supply pipe in the conventional location required an extral long supply tube.