Shutters are offered in three louver sizes: 2 1/2 inch, 3 1/2 inch and 4 1/2 inch. The 3 1/2 inch shutter slat size is the most common shutter size. The 4 1/2 inch shutters are often used for large windows with lots of depth for a grand presentation. 2 1/2 inch louvers slightly resemble the look of blinds from the exterior view of a home, but shutter louvers sizes are truly a personal preference and there is no wrong choice. Many times, window sizes, placement or home size will determine your shutter options.