There are 2 possibilities. Set the flange at either 10" (preferred) or 16". Then select one the Toto models that use the Unifit adapter. These adapter come in 3 sizes. 10", 12", and 14". The toilet is the same for any of these adapters. By selecting the 10" rough in and 10" adapter, your toilet will set exactly where it should. The 16" rough-in and 14" adapter would also work, but would mean the toilet would set out from the back wall by an extra 2". These toilet models come standard with the 12" adapter, but the 10" and 14" cost an additional $50 and no credit for the 12". The advantage of using the adapter is more choices of models that is available with a 10" toilet. These adapters are unique to Toto, no other manufacturer has them. They do not work on toilets that are not designed for them. Any of the Toto models using the Unifit adapter is an excellent performer, so it is a matter of you choice of style. Just go to the "Toilet Review" box at the top of this page, then the "Shopping" link to see all Toto models.