Size really matters!
Especially when it comes to choosing your throne's bidet seat! Measure from the top of your toilet seat to the outer edge of the bowl, and determine if you have an elongated (18-20") or round one (16-18").
If there are any curvatures in the tank or lid overhands, make sure to factor that into the distance from center bolt holes so everything fits nice n' snug.
Time for a royal flush fit? Get measuring!