Matching a new bidet seat to your existing toilet is easy. There are essentially two sizes, elongated and round. We at BidetGenius have used the toilet every single day of our lives, so we can pretty much tell the difference. That said, in order to help everyone out there evaluate, we made this little graphic:

Essentially, round seats measure about 17" inches or less, while elongated measure 17.5" or more. Measure from the fastening holes in the toilet to the front of the rim.

Not every bidet seat comes in a round version, but it's been our experience that they do all come in elongated. Please make sure you order the right one at checkout. If it does not come in round we will not offer it on the site.

New toilet design is making moves to fit elongated seats in the same amount of space as a round toilet, so we're excited to see that play out over the next 75 years.

In addition to knowing if you have an elongated or round seat, it's important to identify if you have a one piece of two piece toilet / bowl combo. If you have a two piece toilet, which is the most common (you know, the old tank and bowl), there is a 98% chance the bidet you're looking at will work. 

A one piece toilet is worth a call to us. This is a toilet where the bowl and tank do not separate. The big thing you need to pay attention to is the junction where the one-piece toilet's bowl and tank meet. If it's a 90 degree angle (similar to a two-piece), you're likely just fine.  If you have a curve that narrows, slopes, swooshes, or french curves, you're in trouble. Check out the Blooming NB-R1063 since this is likely the only one that will fit. You can also replace you're entire unit with a bidet toilet combo like the Bio Bidet IB-835.