Most cushions are 3” with crowning, but the best way to determine the thickness of the cushion is to measure the distance from the place the cushion sits to the floor. A comfortable height for sitting is between 18” and 22”.
You will want the top of the cushion to fall in this range. The scale of the cushion is another consideration, as well as the intended use. We are happy to help answer any of these types of questions you may have. Just call!