This 5 Inch Upholstery Foam (size 5x24x54) is probably the thickest foam you would want to use in your upholstered pieces. 5 Inch Upholstery Foam offers the maximum amount of thickness and support needed in a sofa or chair. Anything thicker could make it uncomfortable when trying to place your feet on the floor. This is also a nice size foam for upholstering seats in a boat or other recreational vehicle. These chairs usually have a width of 25-27 inches and a depth of 18-22 inches.