To properly measure a toilet seat, remove it from the bowl, and measure the width between the middle of the fastening bolt holes. Next, flip the seat over, and measure the greatest width of the seat. Finally, measure the length from between the fastening bolt holes to the bottom.
The typical dimensions for a round or elongated toilet seat are 5 1/2 inches between the fastening bolts, and 14 to 14 1/2 inches for the width. A round seat is usually 16 to 17 inches long, and an elongated seat is typically 18 to 19 inches long.
If you are purchasing a new toilet seat, you must decide between a plastic or a wooden toilet seat. Wooden toilet seats tend to stain from cleaning products and are slightly more expensive than the plastic ones. They also don't hold up as well in a high-moisture bathroom, the paint can chip off them, and the pieces they're made from may separate. However, wooden toilet seats tend to look more attractive, and they are warmer to sit on. Plastic toilet seats are cheaper and last longer, and they may come with add-ons such as slow-closing lids. However, plastic seats are prone to cracking and may show scratches from even the most careful cleaning.