Window tint laws typically specify how opaque each window of an automobile can be. The laws may indicate a different opacity for each window, or varying levels for different types of vehicles. Other factors that may be regulated by these laws include the width of visor shading bands and which types of tinting are allowed. Window tint laws can vary between different jurisdictions, so it is typically advisable to determine the local laws when moving to a new area.
Benefits from window tinting may be both aesthetic and functional. Many people prefer the look of a tinted window, while the opacity may also prevent harmful ultraviolet radiation (UV) from penetrating the vehicle. Window tinting may create a safety hazard if it affects visibility, so tint laws often strike a balance between safety and functionality. There is typically little or no tinting allowed for front windshields, but any level of opacity may be legal for the rear window. Rear side windows often have higher opacity limits than front side windows, which in some areas must remain entirely clear.
In the United States, window tint laws can allow anywhere from 35% visibility to no tint at all on front side windows. Rear side windows can vary from 20% opacity to completely dark, as can back windows. Most areas of the United States also allow for a darker visor band on the front windshield. If this type of visor is allowed, it may be anywhere from four to six inches (about 10 to 15 cm) tall. Other jurisdictions allow this visor to extend to a manufacturer specific line on the windshield, if the vehicle has one.
Trucks and sports utility vehicles (SUVs) may have different regulations under local window tint laws. In many cases, an SUV may only need to conform to window tinting laws for the windshield and front side windows. Some jurisdictions may allow an SUV to have fully opaque side and rear windows.
When window tint laws specify an opacity limit, that number may apply to either the net opacity of both window and tinting film or just the film. If a net percentage is given in a window tint law, then a film with a lower number must be used if the window it is applied to has anything less than perfect light transmission. In other areas, the law may state that the numbers apply to the film only, in which case the opacity of the windows themselves may be ignored.