I have no exact width measurements, but here's something the understand. Although Toto does make and sell toilet seats, toilet seats are universal in size. In other words, you don't have to use a Toto seat on a Toto toilet. If you have a round bowl, then you get a round seat, and if you have an elongated bowl, you get an elongated seat. Go to the plumbing department of a big box store and see their display. What I am getting at is I really don't think there can be much difference in width of any brand. BTW, some of the toilets on your list are really dogs. Now if you are talking about the water spot (the water surface in the bowl) this will vary by model even in the same brand. I have a 1.6 Drake and a 1.6 Dartmouth and both of these have a rather large water spot.