Getting the right light
Slat sizes for shutters are down to personal preference. If you have large windows, french doors or a contemporary look to your home, wide louvres or slats (3 ½" or 4 ½") often work best.
For traditional-style homes or smaller windows, narrow slats (2 ½") could be a better option.
Remember, the wider the slats, the deeper your shutter frame needs to be, so that might influence your choice.