A bidet seat sits on the ceramic – under the toilet seat or, depending on the type, as a complete seat in its place. So it has to fit the ceramic. Two things decide that.
The shape of the bowl. Seen from above, the opening is either equally round at the front and back – a round or O-shape. Or it tapers towards the back and looks like a D lying on its side – the D-shape. The difference is obvious once you look for it. Seats exist for both, and they are not interchangeable.
The hole spacing. At the back of the ceramic are two holes that the toilet seat is bolted through. Their spacing, measured center to center, varies from toilet to toilet. Every bidet seat covers a certain range – 12 to 16 centimeters for our New Standard, 13 to 21 for the Deluxe. A tape measure is enough.
One more thing that helps: the space behind the bowl. The seat adds a few centimeters at the back. If the toilet stands very close to the wall, or the tank sits directly on it, it is worth checking whether there is room there.
If you would rather not measure, take a photo from the side – with the mounting holes and the shut-off valve in frame – and send it to us in the chat. That usually shows straight away whether anything speaks against it.