Matching the seat
If you are buying a bidet seat separately, check its colour code matches the toilet. Most WASHLET models are made in Cotton White and Sedona Beige, so a match is usually available — but not every model comes in every finish.
Comparing colours
Ceramic colour is hard to judge on a screen and monitors vary. Compare in daylight if you can, since bathroom lighting is often warm and makes every white look creamier than it is.
Reading TOTO colour codes
Every TOTO model number ends with a hash and a two-digit code. #01 is Cotton White, #11 is Colonial White, #12 is Sedona Beige, #03 is Bone.
Same toilet, different finish. If you are matching an existing TOTO fixture, the code is usually printed inside the tank lid or on the back of the bowl — matching codes is far more reliable than matching by eye.