The round front toilet seat is the most common type of seat. The dimensions of the seat may vary slightly due to the different manufacturers. The consistent dimension is the bolt spread on the seat's hinges, which is 5 ½” center to center on the bolt post. If the bolt spread is different, you have a proprietary seat. In that case, you will need to know the manufacturer of the toilet and the numbers inside the tank.
The width of the toilet seat is approximately 14”, and the length is measured from the outside front edge of the bowl to the center of the hinge post holes, approximately 16 ½”.
The color of the seat is another distinguishing feature. If the seat is not black or white, you will need to know the manufacturer and the year the toilet was produced to help narrow the color selection.
There are different types of seats:
regular bowl /closed front with cover
regular bowl /open front with cover
regular bowl /open front without cover
There are also many styles of medical lift seats, self-closing seats, seats with grab bars, seats with built in bidets, heated seats and seats with night lights.
The material of the seat is also an important consideration. Seats made of duroplast are the best in terms of quality and durability, but they are available only in a few basic colors. Solid plastic seats are also considered good and durable. Molded wood seats are economical but have limited durability, while light plastic seats are the least expensive and less durable option available.