Minimum width is 9.25 inches. Maximum width is 30 inches for 1.5 inch louver shutters, 40 inches for 2, 50 inches for 3, 4 and 5 inch louver shutters*.Minimum height is 12 inches for single panel shutter and 18 inches for two section panel. Maximum height is 112 for single panel shutter and 133 inches for two section panel. Precision of these measurements are to the quarter inch. Only decimals are accepted. 1/4 = 0.25, 1/2 = .5, 3/4 = .75 Width Height The measurements of the upper and lower rails are approximate due to louver constraints. Precision of these measurements are to the nearest inch (whole numbers only). Actual measurement of the final top and bottom rail may vary by as much as an inch. The minimum height of either rail is 2 inches. Maximum values are constrained only by the height of the entire shutter. The default (and most common) heights are 4 for both upper and lower rails. The middle rail (if one exists) is always 3 inches in height.